Apparatuses and methods for tracking obstructive material within a suction catheter

ABSTRACT

Described here are methods and apparatuses for tracking a clot material within a lumen of a suction catheter. For example, an apparatus as described herein may include a flexible elongate body having a suction lumen, a first pair of electrodes within the suction lumen, a second pair of electrodes proximal to the first pair of electrodes, and a controller configured to track a clot material within the suction lumen based on signals from the first pair of electrodes and the second pair of electrodes.

CLAIM OF PRIORITY

This patent application is a continuation of U.S. patent applicationSer. No. 17/866,462, titled “APPARATUSES AND METHODS FOR TRACKINGOBSTRUCTIVE MATERIAL WITHIN A SUCTION CATHETER,” filed Jul. 15, 2022,now U.S. Patent Application Publication No. 2022/0409857, which is acontinuation of PCT International Patent Application No.PCT/US2022/035392, titled “APPARATUSES AND METHODS FOR CONTROLLINGREMOVAL OF OBSTRUCTIVE MATERIAL,” filed Jun. 28, 2022, which claimspriority to U.S. Provisional Patent Applications No. 63/202,880, titled,“DEVICES, SYSTEMS, AND METHODS FOR SENSING CLOT MATERIAL,” filed on Jun.28, 2021, U.S. Provisional Patent Applications No. 63/203,672, titled“APPARATUSES AND METHODS FOR CONTROLLING REMOVAL OF OBSTRUCTIVEMATERIAL,” filed on Jul. 27, 2021; U.S. Provisional Patent ApplicationsNo. 63/287,049, titled “APPARATUSES AND METHODS FOR CONTROLLING REMOVALOF OBSTRUCTIVE MATERIAL,” filed on Dec. 7, 2021; U.S. Provisional PatentApplications No. 63/310,989, titled “APPARATUSES AND METHODS FORCONTROLLING REMOVAL OF OBSTRUCTIVE MATERIAL,” filed on Feb. 16, 2022;and Provisional Patent Applications No. 63/345,028, titled “APPARATUSESAND METHODS FOR CONTROLLING REMOVAL OF OBSTRUCTIVE MATERIAL,” filed onMay 23, 2022. Each of these is herein incorporated by reference in itsentirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

BACKGROUND

Blockage of blood vessels, including both veins and arteries may resultin serious medical and health issues. For example, a thromboembolism ischaracteristic of numerous common, life-threatening conditions. Examplesof potentially fatal diseases resulting from thrombotic occlusioninclude pulmonary embolism, deep vein thrombosis, and acute limbischemia. Acute pulmonary embolism is a significant cause of death inthe United States. Pulmonary embolism can be a complication from deepvein thrombosis, which has an annual incidence of 1% in patients 60years and older. All of the aforementioned diseases are examples ofconditions in which treatment may include aspiration or evacuation ofclot and/or blood.

However, vacuum-assisted thrombectomy systems must sometimes beterminated due to the risk of excessive blood loss by the patient,especially when using large aspiration catheters. During aspirationthrombectomy, prior to contacting the clot material and/or when thecatheter tip falls out of contact with the clot material (e.g., thrombusor other occlusive material), the tip is exposed to healthy blood andmay remove blood at full flow. Under such conditions, the blood lossrate may be excessive, and in some cases, may result in prematuretermination of the procedure. The blood loss rate may be in the range of20-25 cc per second with an 8 French size catheter. With a maximumtolerable blood loss of 300-1000 mL, the catheter cannot run inunrestricted mode for more than approximately 20 to 50 seconds. When aphysician operates the system manually, the aggregate blood loss mayreach an unacceptable level before sufficient clot is removed. Inaddition, reliably identifying whether the tip of the catheter is incontact with clot or is undesirably aspirating healthy, clot-free bloodis a significant problem, and such manual control is not optimum.

This problem may be exacerbated where clot is hard and difficult toremove, which may delay the time that the suction is applied andlengthen the procedure overall. Although a macerator may be used withclot removal, control of maceration may make guidance and control of thecatheter (e.g., suction catheter) difficult.

It may also be difficult to determine when clot has been taken into thelumen of the aspiration apparatus, including when the aspirationapparatus is clogged. In addition, it would be very helpful toaccurately and/or quantitatively determine how much clot has beenremoved.

It would therefore be desirable to provide methods and apparatuses(e.g., systems, devices, etc.) for controlling the aspiration ofthrombus and clot using aspiration catheters that limits or minimizesblood loss. It would be particularly useful to provide apparatus andmethods including maceration control in which limit or minimize bloodloss during the aspiration procedures. The methods and apparatusesdescribed herein may address these issues.

SUMMARY OF THE DISCLOSURE

Described herein are methods and apparatuses (e.g., devices and/orsystems, including suction/thrombectomy devices, suction/thrombectomycatheters and systems for controlling them) for removing obstructivematerial in a body lumen, such as clot material. Although the followingdiscussion refers mainly to clot material, the present technology isconfigured to remove other types of obstructive material, such as clot(e.g., thrombus) material, e.g., plaque, and/or other obstructivematerial, including vegetation (e.g., bacterial material surrounded by aplatelet/fibrin layer). In general, the methods and apparatusesdescribed herein are configured to control the operation of a suctioncatheter and/or a macerator in conjunction with a suction catheter. Insome embodiments, the present technology comprises one or more sensorsthat are coupled to and/or integrated with one or more components of thetreatment system, such as a suction catheter, which may also be referredto herein as an aspiration catheter. The one or more sensors may providesensor data that the system, including a controller with one or moreprocessors, may analyze to verify the presence of clot material, so thatthe controller may coordinate operation of the suction catheter and/ormacerator. These apparatuses (e.g., devices, systems, etc.) may provideaccurate and rapid confirmation that clot material is near, adjacent to(including in contact with) and/or within the lumen of the aspirationapparatus. In some examples these apparatuses may provide rapid andaccurate estimation of the amount of clot removed. These apparatuses mayalso provide an indication of the rate of removal of the clot (e.g.,travel of the clot material within the lumen of the aspirationapparatus).

The one or more sensors described herein may be positioned at specificlocations on or in the suction catheter and/or (in some optionalexamples) macerator assembly. The location(s) of the sensor may beimportant in providing control information for controlling and/orcoordinating the activity of the suction catheter and/or maceratorassembly. As will be described herein, any appropriate type of sensormay be used, including combinations of different types of sensors.Sensor types may include sensors for detecting an electrical property,such as impedance (e.g., bioimpedance, including bioimpedancespectroscopy), sensors for detecting pressure, and/or sensors fordetecting optical characteristics (e.g., optical spectroscopy). Sensortypes may include ultrasound sensors. Sensor types may include opticalsensors (including sensors for detecting color). Any combination ofthese sensors may be used.

Sensor may be present on a distal and/or lateral external region of thecatheter, and/or within the catheter lumen (e.g., at a distal endregion, proximal end region, and one or more medial end regions). Forexample, pairs of sensing electrodes may be used external and/or withinthe suction catheter.

The methods and apparatuses described herein may generally use thesesensors to provide output (visual, audio, data, etc.) to a user and/orstored for later analysis. For example, these methods and apparatusesmay be used to provide output to a user (e.g., doctor, nurse, surgeon,technician, etc.) that clot material is near, adjacent to and/or withinthe suction catheter. In some examples, these apparatuses may provide anindication that clot material has entered and passed through (or isjammed within) the lumen of the suction catheter. These methods andapparatuses may optionally be used to automatically and/orsemi-automatically control the operation of one or more aspects of theapparatus, such as the application of suction, maceration, etc. Forexample, the apparatus may automatically or semi-automatically controlturning on/off aspiration and/or adjusting the level of aspiration(increasing, decreasing, etc.).

For example, described herein are methods, including methods ofcontrolling a suction catheter. These methods may include: detecting aclot material with a distal end of a suction catheter using a firstsensor or set of sensors on the distal end of the suction catheter;starting or increasing suction through the suction catheter once theclot material has been detected; confirming that the clot material hasbeen drawn into the suction catheter using a second sensor or set ofsensors within the distal end of the suction catheter to detect the clotmaterial within the distal end of the suction catheter; and stopping orreducing the application of suction through the suction catheter afterthe clot material is no longer detected by the first sensor or set ofsensors and the second sensor or set of sensors.

A method may include: inserting a suction catheter into a lumen of ablood vessel; detecting clot material with a distal end of the suctioncatheter using a first sensor and/or set of sensors on the distal end ofthe suction catheter, wherein detecting the clot material comprisesprocessing a signal from the first sensor or set of sensors to confirmthe presence of clot material; starting or increasing suction throughthe suction catheter once the clot material has been detected;monitoring that the clot material has been drawn into the suctioncatheter using a second sensor or set of sensors within the distal endof the suction catheter; and stopping or reducing the application ofsuction through the suction catheter after the clot material is nolonger detected by the first sensor or set of sensors and the secondsensor or set of sensors.

In general, the methods described herein may be used to confirm thepresence and/or proximity of clot material relative to the sensor. Asmentioned, detecting clot material using the first sensor or set ofsensors may comprise detecting the clot material by one or more of:electrical property (e.g., impedance), ultrasound and/or opticaldetection. In particular, detecting the clot material by the firstsensor or set of sensors may comprise detecting clot material byimpedance.

Any of these methods and apparatuses may be configured to start orincrease suction when the controller determines that clot material isnear or on the distal end of the catheter and/or within the catheter,and in particular within the distal end of the catheter. The controllermay process signals from the sensors or sets of sensors to confirm theidentity of clot material, rather than blood, vessel wall, or othernon-clot material. In some examples, multiple sensor types or modalitiesmay be used to confirm the identity of clot material, such asbioimpedance (or bioimpedance spectroscopy) and/or ultrasound and/or oneor more optical properties (e.g., color). The controller may startsuction when the controller determines that clot is nearby one or moreof the sensors. In some examples the suction catheter may include a lowlevel of suction (e.g., between 0.5-50 mmHg); thus, the controller mayincrease the suction to a higher (or high) level of suction when clot isidentified or confirmed (e.g., to greater than about 300 mmHg, greaterthan 350 mmHg, greater than 400 mmHg, etc.).

Similarly, a second sensor and/or set of sensors may be configured tosense the same modality or a different modality from the first sensor orset of sensors. Any of the sensors within the first or second set ofsensors may be configured to sense different modalities (e.g.,impedance, ultrasound, optics, etc.). Thus, any of these methods mayconfirm (using the controller) that the clot material has been drawninto the suction catheter by detecting clot material within the lumen ofthe suction catheter using the second sensor or set of sensors by one ormore of: impedance, ultrasound and/or optical detection.

In general, the methods and apparatuses described herein may process asignal from the first sensor or set of sensors to confirm the presenceof clot material and/or the second sensor or set of sensors to confirmthe presence of clot material. Processing of the sensor signals mayinclude averaging (time averaging), windowing, or the like. Signalprocessing of sensed signals may be analog or digital signal processing,as signals from the sensor(s) may be continuous and/or analog or may besampled with a sample frequency and digitized. Signals may betransmitted in real time to the controller for processing. Thecontroller may process the signals in real time, or with a slight delayto allow for processing. Signals may be processed and/or stored, and/ortransmitted for display and/or storage during a medical procedure.

For example, signals from one or more sensors, including in particularadjacent sensors of the same type or different types may be processedusing one or more analog signal processing techniques, such as byconvolving the signals. Analog signals may be transformed from the timedomain to the frequency domain (e.g., by Fourier transform, Laplaciantransform, etc.) or by expression as a Bode Plot, including withfrequency spectral impedance measurements. Digital signal processing mayalso be performed, e.g., including functional analysis and/or numericalanalysis techniques, such as decomposition into intrinsic mode functionsand/or wavelets. Any of these methods and apparatuses may determinenoise in the sensor to help distinguish and validate contact orproximity to clot material.

The controller may confirm clot material based on characteristics ofsensed values. For example, signals from the first and/or second sensorsor sets of sensors may be processed to reduce noise and/or to amplifysignal and may then be compared to known or expected valuescorresponding to clot material within a predetermined or calculatedconfidence range, to allow the controller to distinguish between clotmaterial, blood and vessel wall. For example, in any of these examples,processing may include processing to distinguish from contacting a lumenwall of a vessel in which the suction catheter is positioned.

The methods and apparatuses described herein may offer numerousadvantages to systems that measure pressure or flow in order to controlthe operation of the suction, but which are unable to confirm theidentity and/or characteristics of clot material. In some cases, themethods and apparatuses described herein may also include sensors fordetecting pressure and/or flow within the lumen of the suction catheter.

In general, these methods and apparatuses may be configured to start orincrease suction after a starting delay. In some examples, the startingdelay may allow further sensing and processing to determine and/orconfirm clot material is present, and/or to allow the user or apparatusto be configured for suction and/or macerating of clot material. Thestarting delay may be, for example, a predetermined delay (e.g., between0.1 second and 10 seconds, between 0.1 second and 8 seconds, between 0.1second and 7.5 seconds, between 0.1 second and 6 seconds, between 0.1second and 5 seconds, between 0.1 second and 4 seconds, between 0.1second and 3 seconds, between 0.1 seconds and 2 seconds, between 0.1second and 1 second, etc.); in some examples the starting delay may bedefined based on user input. For example, in some (semi-automatic)configurations, the apparatus may alert the user that the suction can orshould begin once clot material has been confirmed at or near the distalend of the apparatus and may enable the user to thereafter manuallyinitiate suction. This may be useful for many reasons, includingallowing the user to position the macerator within the lumen of thesuction catheter.

As described above these methods and apparatuses may be configured toallow automatic stopping or reducing of the suction (and/or in someexamples, a macerator, if one is included), including stoppingautomatically after clot material is not detected within the suctioncatheter and distal to the end of the suction catheter. In general,these methods and apparatuses may be configured to stop or reduce theapplication of suction by stopping or reducing the application ofsuction through the suction catheter after a predetermined delay periodonce the clot material is no longer detected by the first sensor or setof sensors and the second sensor or set of sensors. The stop delay maybe, e.g., between 0.1 second and 10 seconds, between 0.1 second and 8seconds, between 0.1 second and 7.5 seconds, between 0.1 second and 6seconds, between 0.1 second and 5 seconds, between 0.1 second and 4seconds, between 0.1 second and 3 seconds, between 0.1 seconds and 2seconds, between 0.1 second and 1 second, etc. In some examples thesystem may emit a stop alert that may indicate stopping of the suctioncatheter (and/or macerator) or may alert the user to manually stopsuction and/or macerator operation. As used herein, an alert may be anaudible alert (tone, chime, etc.) and/or a visible alert (light,indicator, etc.), a tactile alert (e.g., buzzer, vibration, etc.).

Any of the methods described herein may be used for removing clotmaterial from a lumen of the body, such as a blood vessel (e.g., artery,vein, etc.). In some examples, these methods may include methods ofperforming a thrombectomy using suction. The medical method may beperformed with suction alone or in combination with another device orsub-system, such as a mechanical device (e.g., stent-retriever device).The methods and apparatuses described herein may be used in anyappropriate region of the body, including, but not limited to the lungs(e.g., within a pulmonary artery), the peripheral vasculature, theneurovasculature, etc.

Also described herein are apparatuses for performing any of thesemethods, including apparatuses for controlling suction within a suctioncatheter. For example, an apparatus may include: a suction catheter; afirst sensor or set of sensors on a distal end face of suction catheter;a second sensor or set of sensors within the lumen of the suctioncatheter; and a controller comprising one or more processors, whereinthe controller is configured to activate or increase suction through thesuction catheter when a signal from the first sensor and/or set ofsensors indicates that a clot material is in front of the distal end ofthe suction catheter and/or aligned with a certain portion of thesuction catheter (such as an opening(s) in the catheter wall).

Any of these apparatuses may include a macerator within (and/orconfigured to fit within) the lumen of the suction catheter. Additionalexamples of macerators are described below. The macerator may be aseparate element that is slidably disposed within the lumen of thesuction catheter, e.g., can be inserted or removed, within the lumen, orit can be integrated into the suction catheter. As will be described ingreater detail below, the macerator may also be controlled by the samecontroller (or a separate controller) as the suction through the suctioncatheter. The sensors (e.g., first sensor or set of sensors and thesecond sensor or set of sensors) may provide input to the controller (orcontrollers) for processing to identify the presence and/or proximity ofclot material at or near the distal end of the suction catheter as wellas within the lumen of the suction catheter.

The sensor or set of sensors within the lumen of the catheter may bepositioned along all or a portion of the length of the lumen of thecatheter. In some examples the apparatus may include one or more sensorswithin a distal end region of the lumen of the suction catheter. Thedistal end region may include the length of the suction catheter lumenextending proximally from the distal end of the suction catheter towardsa macerator, which may be located more proximally within the lumen ofthe catheter. Any of the examples described herein may include amacerator; however, these methods and apparatuses may also be used oradapted for use without a macerator, as described herein. In someexamples this distal end region may be referred to as the monitoreddistal end region. In some examples the distal end region may have alarger inner diameter than the inner diameter of the more proximalregion of the suction catheter; sensors may be included within thislarger region. Alternatively the distal end region may have the sameouter diameter (or optionally a smaller outer diameter) than the moreproximal region of the catheter, including the region immediatelyproximal. One or more sensors (e.g., in some examples a second sensor orset of sensors) may be contained within the larger diameter distal endregion or they may extend proximally past this larger diameter region.The larger diameter region may be expandable (e.g., may be biased toexpand) as will be described for some examples. In any of theseapparatuses the one or more sensors within the lumen may be coupled (viaa wire or wirelessly) to the controller. Similarly, the one or moresensors on the distal end of the suction catheter (the first sensor orsets of sensors) may be wired or wireless connected to the controller.For example, in any of these apparatuses one or more electricalconnections (wires, lines, traces, etc.) may be made between thesensor(s) and the controller either directly or indirectly. In someexamples each sensor is coupled via a wire or wires extending proximallydown (along the outside or within a sidewall of) the suction catheter toultimately connect to the controller. Separate power and data lines maybe used, or the same (power and data) may be used on the same apparatus.

In some examples the apparatus may include a pump that is coupled to thecontroller. Any appropriate pump providing suction may be used. Forexample, the pump may be a positive displacement pump (e.g., diaphragm,gear, peristaltic, piston pump, etc.) or a dynamic pump (centrifugal,etc.). The pump may be controlled by the controller. For example, thecontroller may output a control signal to turn the pump on, turn thepump off, or adjust the rate or suction applied by the pump. Thus, theapparatus may include a pump coupled to the controller. Optionally, thesuction may be provided by a manually actuated pump (vacuum source).

In some examples the pump is not included directly with the apparatusbut instead (or in addition) the apparatus may include one or morevalves and/or manifolds to modulate a source of suction, e.g., receivedfrom “wall” suction or by a separate pump. Thus, the system may includea suction interface that may control the suction into the suctioncatheter to allow suction (turn on), disallow suction (turn off), oradjust the level of suction (higher/lower, including withinpredetermined ranges of negative pressure). The suction interface may bepart of the controller or may be coupled to the controller. For example,the controller may include one or more valves for adjusting the suctionthrough the suction catheter. In some examples the apparatus may includea pump, and the controller may regulate the applied suction bycontrolling a suction interface, rather than the pump directly.

As mentioned above, the first sensor or set of sensors and/or the secondsensor or set of sensors may one or more of: an acoustic sensor, anelectrical (e.g., bioimpedance sensor), and an optical sensor. Thesensors in the first set of sensors may be the same or different.Similarly, the sensors in the second set of sensors may be the same ordifferent. The first sensor may be the same as the second sensor. Thefirst set of sensors may be the same or different from the second set ofsensors. In some examples, groups of sensors (pairs or sensor, three ormore sensors, etc.) may be combined at a similar location to providemultiple sensing modalities at approximately the same (or the same)location(s). In general, the sensor(s) may be one or more of: anacoustic sensor, an electrical (e.g., bioimpedance) sensor, and anoptical sensor.

In any of these apparatuses the first sensor or set of sensors may bearranged on a deformable cover extending at least partially over thedistal end of the suction catheter. The deformable cover may deform toopen or close to allow clot material into the lumen of the suctioncatheter, while limiting the flow of blood into the suction catheter.The deformable cover may be a sheet of material, e.g., a polymericmaterial, such as but not limited to silicone, that may expand/contract.The deformable cover may include one or more openings, and/or slits,cuts, etc. for allowing the cover to yield to allow clot material intothe cover. In some examples the first sensor or set of sensors may bearranged on the periphery of the distal face opening of the suctioncatheter. The first sensor or set of sensors may generally beforward-looking, e.g., looking distally within the lumen.

As used herein, the term distally or proximally may refer to thedirection away from or towards the body of the user operating thedevice. For example, the distal end of the suction catheter is usuallythe end that is inserted into the subject (e.g., patient) by the userand is moved away from the user into the subject.

As mentioned above, in general these apparatuses may include a set ofsensors (e.g., optionally a second sensor or set of sensors) that arewithin the lumen of the suction catheter, which may be referred to asinternal sensor(s). The internal sensor or set of sensors may bearranged on a sidewall of the lumen of the suction catheter. In someexamples, the internal sensor or set of sensors may be on the maceratorcomponent that is within the lumen of the suction catheter. In someexamples the internal set of sensors may be on both the wall (sidewall)of the lumen and the outside of the macerator (“macerator component”).Thus, in some examples the position of the internal sensor or set ofsensors may be adjustable within the lumen of the suction catheter. Theinternal sensors may optionally be referred to as a second sensor or setof sensors when used with an external sensor or set of sensors. Internalsensors or sensors may be used without an external sensor or set ofsensors (“first sensor or set of sensors).

The one or more processors within the controller may control theapplication of suction through the suction catheter, by controlling thepump directly and/or indirectly (e.g., using one or more valves, etc.)

In some examples the processor may be configured to deactivate ordecrease suction through the suction catheter a predetermined delay time(stop delay) after the signal from the first sensor or set of sensorsindicates that the clot material is not in front of the distal end ofthe suction catheter and the second sensor or set of sensors indicatesthat the clot material is not within the lumen of the suction catheter.The stop delay may be based on a predefined time period (e.g., between0.1 second and 10 seconds, between 0.1 second and 8 seconds, between 0.1second and 7.5 seconds, between 0.1 second and 6 seconds, between 0.1second and 5 seconds, between 0.1 second and 4 seconds, between 0.1second and 3 seconds, between 0.1 seconds and 2 seconds, between 0.1second and 1 second, etc.). In any of these methods and apparatuses, thestop delay may be based on one or more of: a length of the suctioncatheter, a flow rate of material within the suction catheter, and astrength of the suction applied.

For example, described herein are apparatuses including: a suctioncatheter; a first sensor or set of sensors on a distal end face ofsuction catheter; a second sensor or set of sensors within the lumen ofthe suction catheter; and a controller receiving input from the firstsensor or set of sensors and the second sensor or set of sensors andcomprising one or more processors, wherein the one or more processors isconfigured to analyze a signal from the first sensor or set of sensor toconfirm that the a clot material is in contact with or adjacent to thefirst sensor or set of sensors, and to confirm that the clot material iswithin the lumen of the suction catheter based on data from the secondsensor or set of sensors; further wherein the controller is configuredto activate or increase suction through the suction catheter when theone or more processors indicates that the clot material is in front ofthe distal end of the suction catheter, and wherein the controller isconfigured to deactivate or decrease suction through the suctioncatheter a predetermined time period from when the processor indicatesthat the clot material is not in front of the distal end of the suctioncatheter and that the processor confirms that the clot material is notwithin the lumen of the suction catheter.

Also described herein are methods and apparatuses for controlling amacerator within a suction catheter. In any of these apparatuses themacerator may be controlled separately from (or without) control of thesuction through the suction catheter as described above. For example,the methods and apparatuses (systems and devices) described herein mayinclude just methods and apparatuses for controlling a macerator withina suction catheter.

For example, described herein are methods including: applying suction todraw a clot into a suction catheter; detecting a clot material withinthe suction catheter using a sensor or set of sensors within distal endof the suction catheter; driving a macerator within the suction catheteronce the clot material has been detected within the suction catheter;and stopping driving the macerator after the clot material is no longerdetected by the sensor or set of sensors within the suction catheter.

A method may include, for example: applying suction to draw a clot intoa suction catheter; detecting a clot material within the suctioncatheter using a sensor or set of sensors that are positioned on amacerator within a distal end of the suction catheter; driving themacerator once the clot material has been detected; and stopping drivingthe macerator after the clot material is no longer detected by thesensor or set of sensors.

The sensor or set of sensors may be on the macerator. For example, thesensor or set of sensors may be on the outside of the macerator. In someexamples the one or more sensors may be on the distal end region of themacerator near the cutting member (e.g., cutting element) of themacerator. In some examples the one or more sensors may be on the distalend region of the elongated body of the macerator. In general, amacerator may be used to unclog the suction catheter.

The macerator is generally configured to disrupt obstructive material.The macerator may include a wire, blade, or the like, or multiple wires,blades, plates, threads, etc. The cutting member (e.g., wire, blades,threads, etc.) may move, and in some examples may rotate to cut clotmaterial. For example, in some examples a macerator may include aplurality of maceration wires having a linear configuration.Alternatively, or in combination, the maceration wires may be partiallyor fully straight, round, bent, helical about an axis, or have a profilethat is random, or any combination thereof. The macerator may have atits distal end a distal hub coupled to an inner macerator shaft (e.g.,rotating shaft) and at a proximal end may include a proximal hub. Theplurality of maceration wires may be attached to a macerator driveshaft, to the distal hub, or a proximal hub, or any combination thereof.The inner shaft may be concentrically surrounded by an outer shaft. Themacerator inner shaft and outer shaft may be flexible. The inner(rotatable shaft) may be a drive shaft.

In some examples the macerator includes a threaded distal blade within amacerator distal housing having one or more opening for receiving anddisrupting clot material so that it may more easily be removed down thesuction catheter.

Thus, any of the methods described herein may include driving themacerator by driving rotation of the macerator (e.g., the drive shaft)to rotate or otherwise actuate the cutting member of the macerator. Insome examples the macerator may be driven or actuated by extending thecutting member out of a protective housing (e.g., distal housing). Themacerator may be positioned within the lumen of the suction catheter,e.g., by advancing distally within the lumen of the suction catheter.Any of these methods may include extending the macerator within thelumen of the suction catheter prior to applying suction to draw the clotinto the suction catheter.

Any of these methods may also include applying suction by applyingintermittent suction. Suction may be applied in a pattern (e.g., arepeating pattern of high/low negative pressure), or in an oscillatingpattern. Suction may be applied at a constant level.

In any of the methods and apparatuses described herein the clot materialmay be detected by the sensor or set of sensors by sensing one or moreof: impedance (including impedance spectroscopy), ultrasound and/oroptical detection. For example, detecting the clot by the sensor or setof sensors may include detecting clot material by impedance.

Detecting a clot material within the suction catheter using the sensoror set of sensors within distal end of the suction catheter may includedetecting clot material on or adjacent to a window exposing a cutter ofthe macerator.

Also described herein are apparatuses configured to control the actionof the macerator based on the presence and/or proximity of the clotmaterial. For example, described herein are apparatus including: asuction catheter having a suction lumen; a macerator comprising anelongate body, wherein the macerator is configured extend distallythough the suction catheter to a distal end region of the suctioncatheter; a sensor or set of sensors within the lumen of suctioncatheter; and a controller comprising one or more processors, whereinthe controller is configured to activate the macerator when a signalfrom the sensor or set of sensors indicates that a clot material iswithin the lumen of the suction catheter.

As described above, the sensor or set of sensors (in some examples thesecond sensor or set of sensors) may be positioned on the macerator.This sensor or set of sensors may be on the lumen of the suctioncatheter. As discussed above, the sensor or set of sensors may includeone or more of: an acoustic sensor, an electrical (e.g., bioimpedance)sensor, and an optical sensor. In any of these examples, sensors withinthe lumen of the suction catheter may be positioned on a sidewall of thelumen and/or on the macerator.

In any of these methods and apparatuses, the controller may beconfigured to deactivate the macerator when the signal from the sensoror set of sensors indicates that the clot material is longer in thelumen of the suction catheter. For example, the controller may beconnected to a motor driving rotation of a drive shaft for themacerator. The controller may be wired directly or indirectly to themacerator motor (macerator driver). The controller may send digitaland/or analog signals to the macerator to turn on (activate) when clotmaterial is within the lumen of the suction catheter, including whenclot material is near (proximate) to the cutting member of the macerator(and in some cases only when clot material is near the cutting member).The controller may also send digital and/or analog signals to themacerator to turn off (deactivate) when clot material is not within thelumen of the suction catheter and/or when clot material is not near themacerator cutting member. The controller may generally be configured toactivate the macerator by driving rotation of a drive shaft extendingthrough the elongated body.

In some examples the macerator includes one or more side-facing windowsconfigured to expose the cutting member (e.g., a rotating cuttingmember).

For example, described herein are apparatuses including: a suctioncatheter having a suction lumen; a macerator comprising an elongate bodyenclosing a drive shaft, wherein the macerator is configured extenddistally through the suction catheter to a distal end region of thesuction catheter; a sensor or set of sensors on a distal end region ofthe macerator; and a controller comprising one or more processors,wherein the controller is configured to activate the macerator when asignal from the sensor or set of sensors detects a clot material and todeactivate the macerator when the signal from the sensor or set ofsensors does not detect the clot material.

Any of the methods described herein may include controlling both thesuction and the macerator of a suction catheter apparatus by sensingclot and may include any of the component steps of the methods foreither discussed above. For example, described herein are methodsincluding: detecting a clot material with a distal end of a suctioncatheter using a first sensor or set of sensors on the distal end of thesuction catheter; starting or increasing suction through the suctioncatheter once the clot material has been detected; confirming that theclot material has been drawn into the suction catheter using a secondsensor or set of sensors within the distal end of the suction catheterto detect the clot material within the distal end of the suctioncatheter; driving a macerator within the suction catheter once the clotmaterial has been detected within the suction catheter; stopping drivingthe macerator after the clot material is no longer detected by thesecond sensor or set of sensors within the suction catheter; andstopping or reducing the application of suction through the suctioncatheter after the clot material is no longer detected by the firstsensor or set of sensors and the second sensor or set of sensors.

For example, a method may include: inserting a suction catheter into alumen a blood vessel; detecting a clot material with a distal end of thesuction catheter using a first sensor or set of sensors on the distalend of the suction catheter, wherein detecting the clot materialcomprises processing a signal from the first sensor or set of sensors toconfirm the presence of clot material; starting or increasing suctionthrough the suction catheter once the clot material has been detected;monitoring that the clot material has been drawn into the suctioncatheter using a second sensor or set of sensors within the distal endof the suction catheter; driving a macerator within the suction catheteronce the clot material is detected within the suction catheter from thesecond sensor or set of sensors; stopping driving the macerator afterthe clot material is no longer detected by the second sensor or set ofsensors; and stopping or reducing the application of suction through thesuction catheter after the clot material is no longer detected by thefirst sensor or set of sensors and the second sensor or set of sensors.

Any of the apparatuses described herein may also or additional beapparatuses for controlling both suction and maceration of clotmaterial, e.g., controlling both the suction through the suctioncatheter and the operation of the macerator within the suction catheter.For example, an apparatus may include: a suction catheter having asuction lumen; a macerator comprising an elongate body, wherein themacerator is configured extend distally though the suction catheter to adistal end region of the suction catheter; a first sensor or set ofsensors on a distal end face of suction catheter; a second sensor or setof sensors within the lumen of the suction catheter; and a controllercomprising one or more processors, wherein the controller is configuredto activate or increase suction through the suction catheter when asignal from the first sensor or set of sensors indicates that a clotmaterial is in front of the distal end of the suction catheter, furtherwherein the controller is configured to activate the macerator when asignal from the second sensor or set of sensors indicates that a clotmaterial is within the lumen of the suction catheter.

In some examples, the apparatus includes: a suction catheter having asuction lumen a macerator comprising an elongate body enclosing a driveshaft, wherein the macerator is configured extend distally through thelumen of the suction catheter to a distal end region of the suctioncatheter; a first sensor or set of sensors on a distal end face ofsuction catheter; a second sensor or set of sensors within the lumen ofthe suction catheter; and a controller receiving input from the firstsensor or set of sensors and the second sensor or set of sensors andcomprising one or more processors, wherein the one or more processors isconfigured to analyze a signal from the first sensor or set of sensor tovalidate that the a clot material is in contact with or adjacent to thefirst sensor or set of sensors, and to validate that the clot materialis within the lumen of the suction catheter based on data from thesecond sensor or set of sensors; further wherein the controller isconfigured to activate or increase suction through the suction catheterwhen the one or more processors indicates that the clot material is infront of the distal end of the suction catheter, further wherein thecontroller is configured to activate the macerator when a signal fromthe second sensor or set of sensors detects the clot material and todeactivate the macerator when the signal from the second sensor or setof sensors does not detect the clot material, and wherein the controlleris configured to deactivate or decrease suction through the suctioncatheter a predetermined time period from when the processor indicatesthat the clot material is not in front of the distal end of the suctioncatheter and that the processor confirms that the clot material is notwithin the lumen of the suction catheter.

In general, described herein are methods of detecting an obstruction(e.g., clot) to control suction for removing and/or sensing theobstruction using a thrombectomy device (including but not limited to asuction catheter) and/or for controlling a macerator within thethrombectomy device.

For example, any of the methods described herein may include a methodcomprising: moving a thrombectomy device within a blood vessel;detecting an obstruction within an extraction zone distal to anextraction entrance of the thrombectomy device using a sensor configuredto sense the obstruction within the extraction zone of the thrombectomydevice; determining if the obstruction is a vessel wall or a clotmaterial; triggering a clot extraction response if the obstruction isclot material, wherein the clot extraction response comprises one ormore of: signaling to a user that the thrombectomy device is in contactwith clot material, activating an extractor to remove the clot materialfrom the extraction entrance, and/or activating a macerator within anextraction chamber region of the thrombectomy device; and stopping theextractor when clot material is no longer within the extraction chamberregion based at least in part on one or more of: a sensor configured tosense clot material within the extraction chamber region, and a changein macerator response.

Any appropriate thrombectomy device may be used in the methods describedherein, including, but not limited to, thrombectomy devices that applysuction. The thrombectomy device may be mechanical thrombectomy devicesthat remove clot by grabbing and/or otherwise pulling the clot. Forexample, the thrombectomy devices may include stent-based thrombectomydevices or thrombectomy device that pull a mesh or other material toengage and capture clot, either with or without suction.

In general these methods and apparatuses may be configured to determinethe distance between a clot material and a wall of the vessel. The clotmaterial may be a thrombus, atheroma, emboli, plaque, etc. In someexamples the clot material may be within a blood vessel and/or apulmonary vessel. For example, the clot material may be a pulmonaryembolism.

In general, the apparatuses described herein may include an extractionzone that is distal to an extraction entrance of the thrombectomydevice. For example, the extraction zone may be a region within a few mm(e.g., within 10 mm, within 9 mm, within 8 mm, within 7 mm, within 6 mm,within 5 mm, within 4 mm, within 3 mm, within 1 mm, etc.) of theentrance into the portion of the thrombectomy device that removes theclot material. The extraction entrance may be the entrance into achamber of the device, such as the entrance into a suction catheter invariations that remove clot by applying suction. In some examples, theextraction entrance may be at least partially covered; for example, theextraction entrance may be covered by a material, such as a membrane,having an aperture (“extraction aperture” or simply “aperture”) formedtherethrough. The extraction entrance may be covered by afluid-impermeable material; the covering material may be a membrane thatis elastomeric.

Detecting the obstruction within the extraction zone may comprisessensing the obstruction by one or more techniques, such as bybioimpedance. For example, detecting the obstruction within theextraction zone may comprise detecting a change in pressure. Detectingthe obstruction within the extraction zone may comprise opticallydetecting a clot material. Detecting the obstruction within theextraction zone may comprise detecting contact with the obstructionusing a contact sensor.

In some examples, the sensor may comprise a contact sensor and whereindetecting the obstruction within the extraction zone comprises detectingcontact with the contact sensor.

Determining if the obstruction is a vessel wall or a clot material maycomprise applying suction and determining if the obstruction is drawninto the extraction chamber region of the thrombectomy device throughthe extraction entrance. In some examples, determining if theobstruction is a vessel wall or a clot material comprises applyingsuction and determining if the obstruction is drawn into the extractionchamber region of the thrombectomy device a predetermined distancebeyond the extraction entrance. For example, determining if theobstruction is a vessel wall or a clot material may comprise applyingsuction, waiting for 100-1000 milliseconds and determining a change inmacerator response for the macerator within the extraction chamber.Determining if the obstruction is a vessel wall or a clot material maycomprise applying suction and monitoring the pressure within theextraction chamber.

In any of these methods, triggering the clot extraction response maycomprise emitting a signal that the thrombectomy device is in contactwith clot material. The signal may be audible (e.g., a tone, buzz, beep,recorded message, etc.), and/or visual (e.g., a light/LED, display,etc.), tactile (e.g., vibration, resistance, etc.), or the like. In anyof these methods, triggering the clot extraction response may compriseautomatically activating the extractor to remove the clot material fromthe extraction entrance by applying or increasing suction through thethrombectomy device, wherein the extractor comprises a source ofsuction. For example, triggering the clot extraction response maycomprise automatically activating the extractor to remove the clotmaterial from the extraction entrance, wherein the extractor comprises amechanical extractor. In some examples triggering the clot extractionresponse comprises automatically activating or increasing a maceratorwithin the extraction chamber region of the thrombectomy device.Alternatively or additionally, these methods and apparatuses maycomprise emitting a signal that a clot material is (or was) in thesuction catheter, including providing an alert that the suction catheteris clogged and/or where in the lumen of the catheter the clog is present(e.g., distal end region, proximal end region or one or moreintermediate regions).

In any of these methods and apparatuses, detecting the obstructionwithin the extraction zone may comprise detecting the obstruction on anexternal side of a cover covering the extraction entrance of thethrombectomy device, wherein the cover comprises an expandable aperturethrough which clot material may be drawn.

Also described herein are thrombectomy devices that may perform any ofthese methods. For example, an apparatus may comprise: an elongate bodyhaving a suction lumen extending therethrough; an extraction chamberregion at a distal end region of the elongate body in fluidcommunication with the suction lumen; an extraction entrance into theextraction chamber region at a distal end of the extraction chamberregion; an obstruction sensor configured to sense an obstruction in anextraction zone distal to the extraction entrance; and a controllerconfigured to detect an obstruction within the extraction zone using theobstruction sensor, to determine if the obstruction is a vessel wall ora clot material, and to trigger an alert indicating a nature of theobstruction, wherein the controller is further configured for manual orautomatic activation of suction within the extraction chamber regionwhen the controller determines that the obstruction is clot material.

Any of the apparatuses described herein may include a macerator withinthe extraction chamber region configured to macerate clot materialwithin the extraction chamber region.

As mentioned, an of these apparatuses may include a cover over theextraction entrance. The cover may comprise an expandable aperturetherethrough. The aperture may be a slit, cut, flap, or the like. Theextraction chamber region may be expandable.

In any of these apparatuses, the obstruction sensor may comprise acontact sensor. The obstruction sensor comprises a pressure sensor. Theobstruction sensor may comprise an optical sensor. The obstructionsensor may comprise a bioimpedance sensor having two or more electrodes.

Any of these apparatuses may including a suction regulator coupled tothe controller, wherein the controller may be configured to applysuction using the suction regulator to determine if the obstruction is avessel wall or clot material.

In general, any of these apparatuses may include an extraction chamber.The extraction chamber may refer to the distal end region of the suctioncatheter lumen, which may otherwise be similar or identical to theproximal or more intermediate regions of the catheter lumen;alternatively, in some examples the extraction chamber may be astructurally distinct region of the catheter. The extraction chamber maybe partially or fully covered by a cover, as mentioned above. Theextraction chamber may be an expandable region. The extraction chambermay be partially or completely closed off to prevent blood loss into theapparatus (e.g., when drawing suction) or may minimize blood lossthrough the apparatus, as described herein. Thus, in general, theextraction chamber may refer to the distal end region of a catheter(such as a suction catheter) as described herein.

Any of these apparatuses may include an extraction chamber sensorconfigured to detect the obstruction within the extraction chamber; insome examples the controller is configured to determine if theobstruction is a vessel wall or clot material based on an output of theextraction chamber sensor when applying suction. The extraction chambersensor may be one or more of: a contact sensor, a pressure sensor, anoptical sensor, or an electrical (e.g., bioimpedance) sensor. In someexamples, the controller is configured to determine if the obstructionis a vessel wall or clot material based on a change in maceratorresponse.

In general, any of these apparatuses may include a macerator and amacerator driver to drive operation of the macerator. The macerator maybe operated to reciprocate one or more members and/or to rotate one ormore members, driven by the macerator driver. The controller may beconfigured to detect a change in the energy applied to drive themacerator to determine if the obstruction is a vessel wall or clotmaterial. In some examples the controller may be configured to detect achange in vibration of the macerator to determine if the obstruction isa vessel wall or clot material. In any of these apparatuses thecontroller may be configured to determine a load on the macerator or achance in load of the macerator based on the sounds emitted by themacerator and/or driver (e.g., drive shaft, etc.). Thus, any of theseapparatuses may include a microphone input for detecting sounds from theapparatus (e.g., from the macerator).

For example, an apparatus as described herein may include: an elongatebody having a suction lumen extending therethrough; an extractionchamber region at a distal end region of the elongate body in fluidcommunication with the suction lumen; a macerator within the extractionchamber region configured to macerate clot material within theextraction chamber region; an extraction entrance into the extractionchamber region at a distal end of the extraction chamber region; anobstruction sensor configured to sense an obstruction within anextraction zone distal to the extraction entrance; and a controllerconfigured to detect the obstruction within the extraction zone usingthe obstruction sensor, to determine if the obstruction is a vessel wallor a clot material, and to trigger an alert indicating a nature of theobstruction, wherein the controller is further configured for manual orautomatic activation of suction within the extraction chamber regionwhen the controller determines that the obstruction is clot material;wherein the controller is further configured to stop suction through theextraction chamber region when the controller determines that there isno more clot material in the extraction chamber region.

Also described herein are methods of optically detecting clot anddistinguishing wall from clot by spectrometry. For example, a method mayinclude: moving a thrombectomy device within a blood vessel; detectingan obstruction within an extraction zone distal to an extractionentrance of the thrombectomy device using an optical sensor on thethrombectomy device; determining if the obstruction is a vessel wall ora clot material based on reflectance spectral values of the obstruction;triggering a clot extraction response if the obstruction is clotmaterial, wherein the clot extraction response comprises one or more of:signaling to a user that the thrombectomy device is adjacent to clotmaterial, applying suction from the extraction entrance, and/oractivating a macerator within an extraction chamber region of thethrombectomy device; and stopping suction when clot material is nolonger detected within the extraction chamber region.

Any of these methods may include detecting clot material within theextraction chamber region based at least in part on one or more of: asensor configured to sense clot material within the extraction chamberregion, and a change in macerator response. As mentioned, the method mayinclude detecting the obstruction within the extraction zone bydetecting the obstruction on an external side of a cover covering theextraction entrance of the thrombectomy device, wherein the covercomprises an expandable aperture through which clot material may bedrawn. Detecting the obstruction within the extraction zone using theoptical sensor may comprise detecting contact between the optical sensorand the obstruction. In some examples detecting the obstruction with theextraction zone using the optic sensor may comprise detecting anoxygenation level of the obstruction.

In general, triggering the clot extraction response may compriseemitting a signal that the thrombectomy device is in contact with clotmaterial. In some examples triggering the clot extraction responsecomprises automatically activating or increasing suction to remove theclot material from the extraction entrance by applying or increasingsuction through the thrombectomy device. Triggering the clot extractionresponse may comprise automatically activating or increasing maceratoractivity within the extraction chamber region of the thrombectomydevice.

In any of these methods and apparatuses, stopping suction may comprisestopping suction after a predetermined period after clot material is nolonger detected within the extraction chamber region.

Also described herein are methods of mechanically removing clot (withoutor in addition to suction). For example, a method may include: detectingan obstruction within an extraction zone adjacent to an extractionentrance of a thrombectomy device within a blood vessel using an opticalsensor on the thrombectomy device; determining if the obstruction is avessel wall or a clot material based on reflectance spectral values ofthe obstruction; triggering a clot extraction response if theobstruction is clot material, wherein the clot extraction responsecomprises one or more of: signaling to a user that the thrombectomydevice is in contact with clot material, activating an extractor tocapture the clot material, and/or activating a macerator within anextraction chamber region of the thrombectomy device; and stopping theextractor when the clot material is no longer detected within theextraction chamber region.

In some examples, activating the extractor to capture the clot materialcomprises applying suction from the extraction entrance.

Also described herein are thrombectomy device that include one or moreoptical sensor. For example, an apparatus may include: an elongate bodyhaving a suction lumen extending therethrough; an extraction chamberregion at a distal end region of the elongate body in fluidcommunication with the suction lumen; an extraction entrance into theextraction chamber region at a distal end of the extraction chamberregion; an optical sensor configured to sense an obstruction within anextraction zone distal to the extraction entrance; a light sourcecoupled to the optical sensor; an optical detector coupled to theoptical sensor; and a controller coupled to the optical detector andconfigured to detect the obstruction within the extraction zone and todetermine if the obstruction is a vessel wall or a clot material basedon reflectance spectral values of the obstruction, wherein thecontroller is further configured to trigger an alert indicating a natureof the obstruction and to provide for manual or automatic activation ofsuction within the extraction chamber region when the controllerdetermines that the obstruction is clot material.

The optical sensor may comprise a sensing fiber and an emitting fiber.The distal ends of the sensing fiber and emitting fiber may be, in someexamples, embedded within a spherical material having a first index ofrefraction, further wherein the sphere is at least partially coated orcovered with a material having a second index of refraction. Forexample, any of these apparatuses may include a macerator within theextraction chamber region configured to macerate clot material withinthe extraction chamber region; The apparatus may include a cover overthe extraction entrance, the cover comprising an expandable aperturetherethrough. The extraction chamber region may be expandable.

Any of these apparatuses may include a suction regulator coupled to thecontroller, wherein the controller is configured to apply suction usingthe suction regulator to determine if the obstruction is a vessel wallor clot material.

As mentioned, the controller may be further configured to determine ifthe obstruction is a vessel wall or clot material based on a change inmacerator response. Any of these apparatuses may include a maceratordriver, wherein the controller is configured to detect a change in theenergy applied to drive the macerator to determine if the obstruction isa vessel wall or clot material. The controller may be configured todetect a change in vibration of the macerator to determine if theobstruction is a vessel wall or clot material.

For example, an apparatus may include an elongate body having a suctionlumen extending therethrough; an extraction chamber region at a distalend region of the elongate body in fluid communication with the suctionlumen; a macerator within the extraction chamber region configured tomacerate clot material within the extraction chamber region; anextraction entrance into the extraction chamber region at a distal endof the extraction chamber region; an optical sensor configured to sensean obstruction within an extraction zone distal to the extractionentrance; a light source coupled to the optical sensor; an opticaldetector coupled to the optical sensor; and a controller coupled to theoptical detector and configured to detect the obstruction within theextraction zone and to determine if the obstruction is a vessel wall ora clot material based on reflectance spectral values of the obstruction,wherein the controller is further configured to trigger an alertindicating a nature of the obstruction and to provide for manual orautomatic activation of suction within the extraction chamber regionwhen the controller determines that the obstruction is clot material;wherein the controller is further configured to stop suction when clotmaterial is no longer detected within the extraction chamber regionbased at least in part on one or more of: a sensor configured to senseclot material within the extraction chamber region, and a change in themacerator response.

Also described herein are methods of detecting a clot (and/ordistinguishing between a clot material a vessel wall or other material)based on contact pressure. For example, a method may include: moving athrombectomy device within a blood vessel; detecting contact between anobstruction within an extraction zone adjacent to an extraction entranceof the thrombectomy device using a sensor on a distal end of thethrombectomy device in or adjacent to the extraction zone; determiningif the obstruction is a vessel wall or a clot material by applyingsuction from the extraction entrance and detecting the obstructionwithin an extraction chamber region of the thrombectomy device;triggering a clot extraction response if the obstruction is clotmaterial, wherein the clot extraction response comprises one or more of:signaling to a user that the thrombectomy device is in contact with clotmaterial, applying or increasing suction, and/or activating a maceratorwithin an extraction chamber region of the thrombectomy device; andstopping suction when clot material is no longer detected within theextraction chamber region.

Detecting the obstruction within the extraction chamber region may bebased at least in part on one or more of: a sensor configured to senseclot material within the extraction chamber region, and a change inmacerator response. For example, detecting contact may compriseoptically detecting contact. Detecting contact may comprise detectingcontact using a pressure sensor. In some examples, detecting contactcomprises detecting contact using a contact sensing balloon.

In any of these methods, determining if the obstruction is a vessel wallor a clot material by applying suction may comprise applying a pulse ofsuction (e.g., a pulse that is between 5 second and 1 msec, e.g.,between 2 seconds and 1 msec, between 1 second and 1 msec, less than 5seconds, less than 4 seconds, less than 3 seconds, less than 2 seconds,less than 1 second, 900 msec or less, 800 msec or less, 700 msec orless, 600 msec or less, 500 msec or less, 400 msec or less, 300 msec orless, 200 msec or less, 100 msec or less, 75 msec or less, 50 msec orless, etc. In any of these methods and apparatuses the method orapparatus may apply a low-level of constant or variable suction and thepulse may be a pulse of higher suction (e.g., that is 2× higher, 3×higher, 4× higher, 5× higher, 10× higher, 15× higher, 20× higher, 50×higher, 100× higher, etc.).

Any of these methods may include determining if the obstruction is avessel wall or a clot material by detecting clot material using a sensorconfigured to detect the obstruction within the extraction chamber. Forexample, the sensor may include one of: a bioimpedance sensor, anoptical sensor, a pressure sensor, a contact sensor. Determining if theobstruction is a vessel wall or a clot material may include detectingclot material based on a change in response of the macerator, asmentioned above. For example, the change in response of the maceratormay comprise a change in the electrical load of the macerator. Thechange in response of the macerator may comprise a vibrational change ofthe macerator. The change in response of the macerator may comprise anacoustic change of the macerator.

In any of these methods and apparatuses, triggering the clot extractionresponse may comprise emitting a signal that the thrombectomy device isin contact with clot material. Triggering the clot extraction responsemay comprise automatically activating the extractor to remove the clotmaterial from the extraction entrance by applying or increasing suctionthrough the thrombectomy device, wherein the extractor comprises asource of suction. Triggering the clot extraction response may compriseautomatically activating the extractor to remove the clot material fromthe extraction entrance, wherein the extractor comprises a mechanicalextractor. In some examples, triggering the clot extraction responsecomprises automatically activating or increasing a macerator within theextraction chamber region of the thrombectomy device.

Detecting the obstruction within the extraction zone may comprisedetecting the obstruction on an external side of a cover covering theextraction entrance of the thrombectomy device, wherein the covercomprises an expandable aperture through which clot material may bedrawn.

Also described herein are methods of mechanically removing clot (withoutor in addition to suction. In some of these examples suction may be usedto distinguish wall from clot. For example, a method may include: movinga thrombectomy device within a blood vessel; detecting contact betweenan obstruction within an extraction zone distal to an extractionentrance of the thrombectomy device using a sensor on a distal end ofthe thrombectomy device in or adjacent to the extraction zone;determining if the obstruction is a vessel wall or a clot material byapplying suction from the extraction entrance and detecting theobstruction within an extraction chamber region of the thrombectomydevice; triggering a clot extraction response if the obstruction is clotmaterial, wherein the clot extraction response comprises one or more of:signaling to a user that the thrombectomy device is in contact with clotmaterial, activating an extractor to capture the clot material, and/oractivating a macerator within an extraction chamber region of thethrombectomy device; and stopping extraction when clot material is nolonger detected within the extraction chamber region. In any of thesemethods activating an extractor to capture the clot material may includeapplying suction from the extraction entrance.

Also described herein are thrombectomy devices including one or morepressure sensor that are configured to detect clot near or within anextraction chamber. For example, an apparatus comprising: an elongatebody having a suction lumen extending therethrough; an extractionchamber region at a distal end region of the elongate body in fluidcommunication with the suction lumen; an extraction entrance into adistal end of the extraction chamber region; a contact sensor within anextraction zone adjacent to the extraction entrance, wherein the contactsensor is configured to detect a contact pressure; a sensing subsystemconfigured to detect clot material within extraction chamber region; anda controller coupled to the contact detector and the sensing subsystem,and configured to detect contact with an obstruction within theextraction zone based on the contact sensor, and to determine if theobstruction is a vessel wall or a clot material based on the sensingsubsystem, wherein the controller is further configured to trigger analert indicating a nature of the obstruction and to provide for manualor automatic activation of suction within the extraction chamber regionwhen the controller determines that the obstruction is clot material;wherein the controller is further configured to stop suction when clotmaterial is no longer detected within the extraction chamber region.

The sensing subsystem may comprise one or more of: a bioimpedancesensor, a pressure sensor, and an optical sensor. The apparatus mayinclude a macerator within the extraction chamber region configured tomacerate clot material within the extraction chamber region. In any ofthese apparatuses the sensing subsystem may be configured to detect achange in macerator response. As mentioned, any of these apparatuses mayinclude a cover over the extraction entrance, the cover comprising anexpandable aperture therethrough. The extraction chamber region may beexpandable.

Also described herein are methods of detecting clot, e.g., by applying apulse of suction (e.g., on demand or periodically) to see if clot ispulled partially or completely into the extraction chamber and/or intothe cover, and apparatuses configured to perform this method. Thepresence of clot material may be confirmed by detecting a change in themacerator activity and/or by an internal sensor sensing within thechamber. For example, a method may include: detecting clot materialwithin an extraction zone distal to an extraction entrance of athrombectomy device within a blood vessel by applying a pulse of suctionthrough the extraction entrance; confirming the clot material is withinthe extraction zone by detecting clot material within an extractionchamber region of the thrombectomy device during or immediately afterthe pulse of suction; triggering a clot extraction response if clotmaterial is confirmed within the extraction zone, wherein the clotextraction response comprises one or more of: signaling to a user thatthe thrombectomy device is in contact with clot material, activating anextractor to capture the clot material, and/or activating a maceratorwithin an extraction chamber region of the thrombectomy device; andstopping extraction when clot material is no longer detected within theextraction chamber region.

Detecting the clot material within the extraction chamber region may bebased at least in part on one or more of: a sensor configured to senseclot material within the extraction chamber region, and a change inmacerator response. Applying the pulse of suction may comprise applyinga pulse of suction having a predetermined duration of between about 0.1second and 10 seconds. Detecting clot material within the extractionchamber region of the thrombectomy device during or immediately afterthe pulse of suction may comprise detecting clot material using a sensorconfigured to detect the obstruction within the extraction chamber.

The sensor may include one or more of: a bioimpedance sensor, an opticalsensor, a pressure sensor, a contact sensor. Alternatively oradditionally, detecting clot material within the extraction chamberregion of the thrombectomy device during or immediately after the pulseof suction may comprise detecting clot material based on a change inresponse of the macerator. The change in response of the macerator maycomprises a change in the electrical load of the macerator and/or avibrational change of the macerator and/or a change in the sound of themacerator, e.g., an acoustic change of the macerator.

In any of these examples, triggering the clot extraction responsecomprises emitting a signal that the thrombectomy device is in contactwith clot material. Triggering the clot extraction response may compriseautomatically activating the extractor to remove the clot material fromthe extraction entrance by applying or increasing suction through thethrombectomy device, wherein the extractor comprises a source ofsuction. Triggering the clot extraction response may compriseautomatically activating the extractor to remove the clot material fromthe extraction entrance, wherein the extractor comprises a mechanicalextractor. Triggering the clot extraction response may compriseautomatically activating or increasing a macerator within the extractionchamber region of the thrombectomy device.

Detecting the clot material within the extraction zone may compriseapplying the pulse of suction through an expandable aperture within acover covering the extraction entrance of the thrombectomy device

For example, a method may include: moving a thrombectomy device within ablood vessel; detecting a clot material within an extraction zoneadjacent to an extraction entrance of the thrombectomy device byapplying a pulse of suction through the extraction entrance whileoperating a macerator within an extraction chamber region of thethrombectomy device during or immediately after the pulse of suction,and confirming clot material within the extraction zone based on achange in macerator response; triggering a clot extraction response ifclot material is confirmed within the extraction zone, wherein the clotextraction response comprises one or more of: signaling to a user thatthe thrombectomy device is in contact with clot material, activating amechanical extractor to capture the clot material, and/or activating amacerator within an extraction chamber region of the thrombectomydevice; and stopping extraction after clot material is no longerdetected within the extraction chamber region based on a change inmacerator response.

Also described herein are apparatus comprising: an elongate body havinga suction lumen extending therethrough; an extraction chamber region ata distal end region of the elongate body in fluid communication with thesuction lumen; an extraction entrance into a distal end of theextraction chamber region; a macerator within the extraction chamberregion; and a controller configured to couple to a suction regulator andto control the application of a pulse of suction from the suctionregulator through the extraction entrance when the macerator is runningand to confirm the presence of clot material within the extractionchamber region by detecting a change in a macerator response during thepulse of suction, further wherein the controller is configured toperform one or more of: signal the presence of a clot material, activatea suction to capture the clot material, activate the macerator and/orstop suction after clot material is no longer detected within theextraction chamber region based on the macerator response during captureof the clot material.

Also described herein are methods of detecting clot using sensors thatdetect opening of the aperture into the extraction chamber (e.g.,separation of the side of the aperture that are partially of fullyclosed). For example, a method may include: moving a thrombectomy devicewithin a blood vessel; detecting clot material within an extraction zoneadjacent to an extraction entrance of the thrombectomy device byapplying a pulse of suction through the extraction entrance anddetecting a separation between two or more sides of an aperture througha cover over the extraction entrance of the thrombectomy device;triggering a clot extraction response if the separation between the twoor more sides exceeds a threshold, wherein the clot extraction responsecomprises one or more of: signaling to a user that the thrombectomydevice is in contact with clot material, activating suction to capturethe clot material, and/or activating a macerator within the extractionchamber region.

Any of these methods may include stopping the clot extraction responsewhen clot is no longer detected outside of the extraction region and/orwithin the extraction chamber, either immediately or after a delay(permitting clot material already within the apparatus to be cleared).For example, any of these methods and apparatuses may be configured tostop the clot extraction process after the separation between the two ormore sides no longer exceeds the threshold while applying suction.

Detecting the separation between two or more leaflets may comprisedetecting separation between two or more electrodes on the leafletsbased on an impedance measurement. Detecting the separation between twoor more leaflets may comprise optically detecting separation between thetwo or more leaflets.

Also described herein are apparatus comprising: an extraction chamberregion at a distal end region of an elongate body in fluid communicationwith a suction lumen; an extraction entrance into the extraction chamberregion; a cover covering the extraction entrance; an aperture throughthe cover, the aperture having two or more sides; a sensor configured todetect a separation between the two or more sides of the aperture; and acontroller configured to couple to a suction regulator and to controlthe application of a pulse of suction from the suction regulator throughthe extraction entrance and to trigger a clot extraction response if theseparation between the two or more sides exceeds a threshold, whereinthe clot extraction response comprises one or more of: signaling contactwith a clot material, activating suction to capture the clot material,and/or activating a macerator within the extraction chamber region. Theapparatus may include a macerator within the extraction chamber region.The controller may be further configured to stop suction after theseparation between the two or more sides is less than the threshold.

In general, described herein are apparatuses for detecting a clotmaterial within an aspiration catheter (having a suction lumen) using asensor that is within (or at least partially within) the suction lumen.In some examples the sensor is a deflection sensor, that includes adeflectable member. The apparatus (e.g., a controller and/or sensingcircuitry) may detect deflection of the deflectable member in order toconfirm that clot material is present within the suction lumen, and/orto distinguish between clot material at the distal end or distal endregion of the device and vessel wall.

For example, described herein are apparatuses including: an elongatebody having a suction lumen extending therethrough; a deflection sensorextending at least partially into the suction lumen, the deflectionsensor comprising a deflectable member having a first region that iscoupled to a wall location within the suction lumen and a second regionseparated from the first region by a length of the deflectable member,wherein the deflectable member has an undeflected configuration and adeflected configuration, wherein in the deflected configuration thesecond region has an axially offset relative to the wall location thatis different from the axial offset between the second region and thewall location in the undeflected configuration; and a controllerconfigured to detect an obstruction within the suction lumen based on asignal from the deflection sensor indicating a deflection of thedeflectable member.

The deflectable member may be configured as an elongate member thatprojects into and/or across the suction lumen (e.g., across the distalend region, also referred to herein as the clot extraction chamberregion, of the suction lumen). The deflectable member may be arranged,in the first configuration, transverse to the long axis of the suctionlumen. In some examples the deflectable member may be arranged along thelongitudinal axis and/or helically wound around the longitudinal axis(as a spring, etc.). In some examples the deflectable member may bereferred to as whisker; for example, the deflectable member may comprisea deflectable whisker.

The deflectable sensor may comprise a first electrode at the firstregion and a second electrode on a wall of the suction lumen oppositefrom the deflectable member, wherein when the deflectable member is inthe undeflected configuration the deflectable member extends across thesuction lumen so that the first electrode is proximate to the secondelectrode, and when the deflectable member is in the deflectedconfiguration the first electrode and the second electrode are axiallyspaced further apart as compared to the undeflected configuration. Insome examples the apparatus may include a third electrode that isaxially spaced within the suction lumen relative to the wall location sothat in the deflected configuration the first electrode is closer to thethird electrode than as compared to the undeflected configuration.

In some examples the deflectable member comprises a shape sensingoptical fiber. Alternatively or additionally, in some examples thedeflectable member comprises a piezoelectric material. For example, thecontroller may be configured to detect transitioning of the deflectablemember between the undeflected and deflected configurations based on apiezoelectric signal. In some examples the deflectable member comprisesa variable resistive material that changes resistivity when bending; thecontroller may be configured to detect a change in resistance as thedeflectable member bends.

In any of these examples, the controller may be configured to determineif the obstruction is a vessel wall or a clot material. For example, thecontroller may be configured to use a signal from the deflection sensorthat represent deflection of the deflectable member, and/or or more ofpressure with the suction lumen and/or flow within the suction lumen todetermine if a clot material is stuck within the suction lumen,including in particular at a distal end of the suction lumen (oftenreferred to as “lollypopping” in which a portion of a large clot isstuck in the distal end region of the

In some examples the deflectable member is in a distal end region of thesuction lumen that is configured as an extraction chamber region. Thedeflectable member may extend proud from the wall of the suction lumenin the first configuration and may be configured to deflect so that thesecond region of the deflectable member is axially and radiallydisplaced relative to the undeflected configuration. In some examplesthe extraction chamber region is expandable; alternatively, in someexamples the extraction chamber region is not differentiated from therest of the suction lumen but refers to a distal region of the suctionlumen at the distal end of the apparatus. In any of these apparatuses,the wall location within the suction lumen is within about 5 mm from adistal end of the suction lumen of the elongate body.

The deflectable member may generally be configured to couple to the wallof the suction lumen at a first region (e.g., first end) an to deflector deform so that a second region (e.g., second end region) of thedeflectable member moves relative to the first region when a force isapplied by a material within the suction lumen, such as blood or clotmaterial. In general, the deflectable member is configured toelastically deflect so that it returns to the first (undeflected)configuration when the force from interacting with material in thesuction lumen is removed. In some cases the deflectable member is formedof a superelastic material such as a nickel-titanium material (e.g.,Nitinol) and/or a polymeric material. The deflectable member maycomprise a polymeric inner liner, a reinforced layer, and a polymericouter jacket. In some examples, in the first configuration the firstelectrode is separated from the second electrode by between about 0.01mm and about 2 mm.

In any of these apparatuses the suction lumen may be covered orpartially covered. F or example, the apparatus may include a cover overa distal end of the suction lumen, the cover having an expandableaperture therethrough. In any of these apparatuses the suction lumen maybe surrounded by a deformable lip.

Any of these apparatuses may include a macerator within the suctionlumen and configured to macerate clot material within the suction lumen.Any of these apparatuses may include a macerator drive. The controllermay control the application of energy to drive the macerator (e.g., torotate a drive shaft/drive wire of the macerator) either manually orautomatically. In some examples the controller is configured to applypulsed suction.

As mentioned, the apparatus may include a pressure sensor configured todetermine pressure within the suction lumen. Any of these apparatusesmay include a flow sensor configured to determine flow through thesuction lumen.

The controller may be configured to trigger an alert indicating a natureof the obstruction. The controller may be configured for manual orautomatic activation of suction when the controller determines that theobstruction is clot material.

Any of these apparatuses may include one or more stops within thesuction lumen to prevent advancing of a macerator distally over thedeflectable member.

The apparatuses described herein may include multiple deflection sensorswithin the suction lumen. For example, the apparatus may include asecond deflectable member extending from a wall of the suction lumen,wherein the second deflectable member is located at a more proximalregion of suction lumen.

For example, described herein are apparatuses (e.g., thrombectomyapparatuses) configured for removing material from within a vessel usingone or more deflectable whiskers to confirm and/or detect the presenceof clot material and/or to distinguish between clot material and vesselwall. Any of these apparatuses may include: an elongate body having asuction lumen extending therethrough; a deflectable whisker extendingfrom a wall of the suction lumen; a first electrode at a distal endregion of the deflectable whisker; a second electrode on the wall of thesuction lumen opposite from the deflectable whisker, wherein thedeflectable whisker has a first configuration in which the deflectablewhisker extends across the suction lumen so that the first electrode isproximate to the second electrode, and a second configuration in whichthe deflectable whisker is deflected so that the first electrode isspaced further apart from the second electrode as compared to the firstconfiguration; and a controller configured to detect an obstructionwithin the suction lumen based on an electrical signal between the firstelectrode and the second electrode, indicating deflection of thedeflectable whisker.

In some examples the apparatus may include: an elongate body having asuction lumen extending therethrough, wherein a distal end region of thesuction lumen is configured as an extraction chamber region; adeflectable whisker extending from a wall of the extraction chamberregion; a first electrode at a distal end region of the deflectablewhisker; a second electrode on the wall of the suction lumen oppositefrom the deflectable whisker, wherein the deflectable whisker has afirst configuration in which the deflectable whisker extends proudacross the extraction chamber region so that the first electrode isproximate to the second electrode and a second configuration in whichthe deflectable whisker is deflected so that the first electrode isspaced apart from the second electrode as compared to the firstconfiguration; and a controller configured to detect an obstructionwithin the extraction chamber region based on an electrical signalbetween the first electrode and the second electrode and to determine ifthe obstruction is a vessel wall or a clot material.

In any of these apparatuses the controller may be configured todetermine if the obstruction is a vessel wall or a clot material. Forexample, the controller may include one or more processors that mayanalyze the electrical signal (e.g., impedance, conductance, etc.)between the first and second electrode and, based on the electricalproperties over time (e.g., a comparison between the impedance before,during and/or after the application of suction, such as a pulse ofsuction) to determine if the whisker is deflected because of clotmaterial within the suction lumen, e.g., within the extraction chamberregion.

In any of these apparatuses and methods, the deflectable whisker may bein a distal end region of the suction lumen configured as an extractionchamber region. The deflectable whisker may extend proud from the wallof the suction lumen in the first configuration and may be deflected sothat the distal end region of the deflectable whisker is axially andradially displaced relative to the second electrode in the secondconfiguration. The extraction chamber region may be expandable, asdescribed above.

In some examples, the deflectable whisker may be within about 5 mm froma distal end of the suction lumen of the elongate body. The deflectablewhisker may include a superelastic material. In some examples thedeflectable whisker comprises a polymeric inner liner, a reinforcedlayer, and a polymeric outer jacket.

In any of these examples the apparatus may include a cover over a distalend of the suction lumen, and the cover may have an expandable aperturetherethrough.

Any of these apparatuses may include a macerator within the suctionlumen and configured to macerate clot material within the suction lumen,as described above. The macerator may be prevented from damaging thedeflectable whiskers, either by limiting the travel of the maceratorwithin the suction lumen (e.g., preventing it from traveling over thewhisker) and/or including one or more features on the macerator, such asa distally-extending sleeve or cuff that deflects the deflectablewhisker distally and away from the macerator opening(s).

Any of these apparatuses may include a pressure sensor configured todetermine pressure within the suction lumen, and/or a flow sensor (e.g.,a thermal anemometer, such as a hot-wire anemometer). To determine flowwithing the suction lumen.

Any of these apparatuses may include a macerator driver. The controllermay control the drive (e.g., drive wire) of a rotating cutting elementwithin the macerator.

In any of these apparatuses, the controller may be configured to applypulsed suction. The use of pulsed suction may allow the apparatus todetermine that clot material is present.

In any of these apparatuses, the controller may be configured to triggeran alert indicating a nature of the obstruction. The controller may befurther configured for manual or automatic activation of suction whenthe controller determines that the obstruction is clot material.

The apparatuses described herein may include a plurality of deflectablewhiskers. For example, the apparatus may include a second deflectablewhisker extending from a wall of the suction lumen, wherein the seconddeflectable whisker is located at a more proximal region of suctionlumen.

In some examples the first firs electrode may be kept separate (e.g.,non-contracting) the second electrode. This may enhance sensitivity ofthe apparatus. For example the first electrode may be separated from thesecond electrode by between about 0.01 mm and about 2 mm.

Also described herein are methods of controlling an apparatus asdescribed herein, and/or methods of removing a clot material, and/ormethods of distinguishing a clot material from a vessel wall. Thesemethods may be particularly well suited for removing clot materialwithout removing an excess of blood.

For example, a method may include: applying suction through a suctionlumen of a device within a blood vessel; detecting deflection of adeflectable member extending at least partially within an extractionchamber region at a distal end region of the suction lumen; determiningif the deflection was caused by a clot material caught in the extractionchamber region; triggering a clot extraction response if clot materialis caught in the extraction chamber region, wherein the clot extractionresponse comprises one or more of: signaling to a user that the deviceis adjacent to clot material, applying continuous suction through thesuction lumen, and/or activating a macerator within an extractionchamber region of the device.

Applying suction may include applying a pulse of suction. Pulsingsuction may allow the apparatus to detect clot material and/or removeclot material without removing an excessive amount of blood from thesubject. The pulse of suction may be, e.g., 2 seconds or faster (e.g.,1.5 sec or faster, 1 sec or faster, 0.9 seconds or faster, 0.7 sec orfaster, 0.6 sec or faster, 0.5 sec or faster, 0.4 sec or faster, 0.3 secor faster, 0.2 sec or faster, 0.1 sec or faster, 50 msec or faster, 10msec or faster, 5 msec or faster, 1 msec or faster, etc.).

Any of these methods may include stopping suction when the deflectablemember indicates that clot material is no longer within the extractionchamber region and/or no longer within the suction lumen (e.g., usingone or more deflectable members). Stopping suction may include stoppingsuction after a predetermined period after clot material is no longerdetected within the suction lumen (e.g., after 1 second, after 2seconds, after 3 seconds, after 4 seconds, after 5 seconds, after 6seconds, after 7 seconds, after, 8 seconds, after 9 seconds, after 10seconds, after, 12 seconds, after 15 seconds, etc.). Suction may bemanually or automatically stopped.

Any of these methods may include sensing one or more of: a pressurewithin the suction lumen and/or a flow rate through the suction lumen.The method may further include using one or more of pressure within thesuction lumen and/or flow rate through the suction lumen to determinethat a clot material is within (e.g., trapped within) the suction lumen.Any of these methods may also include using one or more of pressurewithin the suction lumen and/or flow rate through the suction lumen todistinguish between vessel wall and clot material.

Triggering the clot extraction response may include emitting a signalthat the device is in contact with clot material. In some examplestriggering the clot extraction response comprises automaticallyactivating or increasing suction to remove the clot material from theextraction chamber region by applying or increasing suction through thesuction lumen. Alternatively or additionally triggering the clotextraction response may comprise automatically activating or increasingmacerator activity within the extraction chamber region.

The deflectable member may be part of a deflection sensor thatidentifies deflection of the deflectable member by sensing one or moreparameters, such as electrical or mechanical parameters. The deflectablemember may be part of a sensing circuit configured to detect the changein shape or deflection of the deflection member within the suction lumen(or a region of the suction lumen, such as the extraction chamberregion. Note that in any of the apparatuses described herein a distinctextraction chamber region may be included as part of or in fluidcommunication with the suction lumen. Alternatively in some examples theextraction chamber region may be an unpartitioned (undivided) section ofthe suction lumen (e.g., at or near the distal end).

For example, detecting deflection of the deflectable member comprisesdetecting a change in a resistance, conductance or inductance of thedeflectable member. In some examples detecting deflection of thedeflectable member comprises detecting a change in shape of thedeflectable member using an optical fiber bend sensor. In some examplesdetecting deflection of the deflectable member comprises detecting achange in voltage or current in a sensing circuit to which thedeflectable member is electrically coupled.

For example, a method may include; moving a device within a bloodvessel; applying suction through a suction lumen of the device;detecting an obstruction within an extraction chamber region at a distalend region of the suction lumen through the device using a deflectablewhisker extending at least partially across the extraction chamberregion; determining if the obstruction is a vessel wall or a clotmaterial based on an electrical signal between a first electrode at adistal end of the deflectable whisker and a second electrode incommunication with a wall of the extraction chamber region; triggering aclot extraction response if the obstruction is clot material, whereinthe clot extraction response comprises one or more of: signaling to auser that the device is adjacent to clot material, applying continuoussuction through the suction lumen, and/or activating a macerator withinan extraction chamber region of the device.

In any of these methods, applying suction may include applying a pulse(or pulses) of suction.

Any of these methods may include stopping suction when clot material isno longer detected within the extraction chamber region. For example,stopping suction may include stopping suction after a predeterminedperiod after clot material is no longer detected within the suctionlumen.

These methods may also include sensing one or more of: a pressure withinthe suction lumen and/or a flow rate through the suction lumen.

As described above, triggering the clot extraction response may compriseemitting a signal that the device is in contact with clot material. Forexample, triggering the clot extraction response may compriseautomatically activating or increasing suction to remove the clotmaterial from the extraction chamber region by applying or increasingsuction through the suction lumen. In some examples triggering the clotextraction response comprises automatically activating or increasingmacerator activity within the extraction chamber region.

Also described herein are methods of performing a pulmonary embolectomy.For example, a method of performing a pulmonary embolectomy may include:advancing an aspiration catheter into a pulmonary artery (e.g., in someexamples, the left pulmonary artery); applying aspiration through theaspiration catheter; determining, when flow through the aspirationcatheter is occluded, an identity of the occlusion as clot material oras vessel anatomy; and outputting an indicator of the identity of theclot material. Advancing the aspiration catheter may comprise advancingthe aspiration catheter through a pulmonic valve and around a bend intothe pulmonary artery.

In general, determining the identity of the occlusion as clot materialor as vessel anatomy may include detecting clot material using anintraluminal sensor. For example, determining the identity of theocclusion as clot material or as vessel anatomy may comprise deflectinga deflectable member within a lumen of the aspiration catheter.Determining the identity of the occlusion as clot material or as vesselanatomy may comprise optically confirming that the occlusion is clotmaterial.

In any of these examples, outputting the indicator may comprisetriggering an alert to a user. Outputting the indicator may comprisestopping the application of aspiration when the identity of theocclusion is vessel anatomy.

Also described herein are methods and apparatuses for determiningcharacteristics of the clot material within the suction lumen. Forexample, described herein are apparatuses comprising: an elongate bodyhaving a suction lumen extending therethrough; a first internalimpedance sensor at a distal end region of the suction lumen; a secondinternal impedance sensor at a proximal region of the suction lumen; anda controller configured to track a clot material within the suctionlumen based on a signal from the first internal impedance sensor and thesecond internal impedance sensor.

For example, an apparatus may include: an elongate body having a suctionlumen extending therethrough; a first internal impedance sensor at adistal end region of the suction lumen comprising a first pair ofannular electrodes extending adjacently at least partially around thesuction lumen; a second internal impedance sensor at a proximal regionof the suction lumen comprising a second pair of annular electrodesextending adjacently at least partially around the suction lumen; and acontroller configured to track a clot material within the suction lumenbased on an impedance signal over time from the first internal impedancesensor and an impedance signal over time from the second internalimpedance sensor and to determine a size estimate of the clot material.

The first internal impedance sensor may comprise a pair of annularelectrodes extending radially around the suction lumen. In some examplesthe annular electrodes comprise ring electrodes extending radiallyaround the suction lumen (completely or partially). In some examples theannular electrodes comprise helical electrodes. The pair of annularelectrodes may be separated from each other by between 1 and 20 mm(e.g., between 5 mm and 20 mm, between 5 mm and 10 mm, etc.). The pairof annular electrodes may each extend greater than 40 degrees radiallyaround the suction lumen. Either or both the first impedance sensor orthe second impedance sensor (or both) may include an alternatingelectrical power source configured to establish and control a variablevoltage between the annular electrodes of the first internal impedancesensor. The controller may be further configured to determine a size ofthe clot material based on the signal from the first internal impedancesensor and the second internal impedance sensor. In some examples thecontroller is configured to determine a rate of flow of the clotmaterial within the suction lumen. The controller may be configured todistinguish between clot material and vessel wall based on the signalfrom the first internal impedance sensor and the second internalimpedance sensor. In some examples the controller is further configuredto modulate suction through the suction catheter based on at least thesignal from the first internal impedance sensor.

Also described herein are methods of tracking clot material within thesuction catheter by detecting an impedance signal over time from a firstimpedance sensor (e.g., a first pair of annular electrodes) in thedistal end region of the suction lumen and by detecting an impedancesignal over time from a second impedance sensor at a proximal region ofthe suction lumen. The method may include identifying matching patternsrepresenting the clot material from both the first impedance sensor andthe second impedance sensor and determining the time delay between thematching patterns to estimate the rate of travel of the clot materialwithin the suction lumen. The method may also include estimating thetime that the clot material took to pass the second impedance sensor atthe proximal end of the suction lumen to estimate a length of the clotmaterial and/or using a known cross-sectional area of the suction lumento estimate an amount (e.g., volume, size, etc.) of the clot materialremoved.

Any of these methods may include applying an alternating electricalpower (e.g., AC Voltage) to establish and control a variable voltagebetween the sensing electrodes forming the first impedance sensor and/orthe second impedance sensor. Separate AC voltages may be applied fromdifferent or the same AC voltage source. Any of the these methods mayinclude distinguishing between the vessel wall and clot material usingsignals form the first impedance sensor and the second impedance sensor.

Any of these methods may include outputting the tacking data, e.g.,outputting the rate of removal of the clot material and/or outputtingthe size (e.g., length, volume, etc.) of clot material removed throughthe suction lumen, and/or outputting the presence and/or location of aclot within the suction lumen.

For example, in general, described herein are methods of detectingand/or tracking clot material within the lumen of the suction catheterusing impedance sensing. These methods and apparatuses may beparticularly useful for determining if clot material is still in thelumen of the catheter. In general, it may be very helpful to know ifclot material is within the lumen, as if clot material is stuck in thelumen, the suction/pressure alone may not be sufficient to detect thematerial. When clot material is stuck within the lumen, the physicianmay need to know this including when it is desired to apply contrastthrough the lumen. If clot material is still present in the catheter,clot material may be driven back out and into the patient, which couldlead to more problems for the patient. For example, described herein areapparatuses comprising: a flexible elongate catheter having a suctionlumen extending therethrough; an internal electrical impedance sensorcomprising two or more electrodes within the suction lumen; and acontroller coupled to the internal electrical impedance sensor andconfigured to apply an alternating current between the two or moreelectrodes and to detect an obstructive material within the suctionlumen based on electrical impedance signals from the internal electricalimpedance sensor.

In any of these apparatuses, the internal electrical impedance sensormay be configured to operate at 50 kHz or greater (e.g., 100 kHz orhigher, etc.). The internal electrical impedance sensor may be withinabout 20 mm of an aspiration opening into the suction lumen at a distalend region of the flexible elongate catheter. The controller may befurther configured to output a signal indicating obstructive material iswithin the suction lumen.

The controller may be configured to apply the alternating current afterbeginning suction through the suction lumen.

Any of these apparatuses may include a second internal electricalimpedance sensor comprising two or more electrodes at a proximal regionof the suction lumen.

The apparatus may include a current generator configured to apply thealternating current.

In general, the two or more electrodes may be any appropriate electrode.In some example, the two or more electrodes comprise annular electrodesextending at least partially radially around the suction lumen. Forexample, the annular electrodes may comprise helical electrodes. Theannular electrodes may be separated from each other by between 0.1 and20 mm. The annular electrodes may each extend 30 degrees or moreradially around the suction lumen.

For example, described herein are apparatus comprising: a flexibleelongate catheter having a suction lumen extending therethrough; aninternal electrical impedance sensor comprising two or more electrodeswithin the suction lumen between a proximal and a distal end of theflexible elongate catheter; and a controller coupled to the internalelectrical impedance sensor and configured to apply an alternatingcurrent between the two or more electrodes, to detect an obstructivematerial within the suction lumen based on electrical impedance signalsfrom the internal electrical impedance sensor, and to output a signalindicating obstructive material is within the suction lumen.

In general, these apparatuses may include just the catheter (for usewith a controller and other system components) or may include just thecontroller and other system components for use with a catheter asdescribed herein. For example, the apparatus may include comprising: aflexible elongate catheter having a suction lumen extendingtherethrough; an aspiration opening at a distal end region of theflexible elongate catheter; a first internal electrical impedance sensorcomprising two or more electrodes extending at least partially aroundthe suction lumen at a distal end region of the suction lumen; a secondinternal electrical impedance sensor comprising two or more electrodesextending at least partially around the suction lumen at a proximalregion of the suction lumen; and one or more connectors at a proximalend region of the flexible elongate catheter, wherein the one or moreconnectors are in electrical communication with the first internalelectrical impedance sensor and the second internal electrical impedancesensor, further wherein the one or more connectors are configured tocouple to a controller to provide electrical impedance input to detectan obstructive material within the suction lumen based on electricalimpedance signals from the first internal electrical impedance sensorand the second internal electrical impedance sensor.

The first internal electrical impedance sensor may be within about 20 mmof an aspiration opening into the suction lumen. Any of theseapparatuses may include a proximal suction port in communication withthe suction lumen. The aspiration opening may be on a tapered side ofthe distal end region of the flexible elongate catheter. The two or moreelectrodes of the first internal electrical impedance sensor maycomprise annular electrodes. The annular electrodes of the firstinternal electrical impedance sensor may comprise helical electrodes.The annular electrodes of the first internal electrical impedance sensormay be separated from each other by between 0.1 and 20 mm. The annularelectrodes of the first internal electrical impedance sensor may eachextend 30 degrees or more radially around the suction lumen.

Also described herein are methods of detecting an obstructive materialwithin a lumen of an aspiration catheter, the method comprising:applying suction through a lumen of the aspiration catheter; applying avariable current between two or more electrodes of a first internalelectrical impedance sensor within the lumen of the aspiration catheterbetween a proximal and distal ends of the aspiration catheter togenerate an impedance signal; and detecting the obstructive materialwithin the lumen of the aspiration catheter based on the impedancesignal. Detecting the obstructive material may comprise distinguishingobstructive material from blood within the lumen of the aspirationcatheter based on the impedance signal. Any of these methods may includeoutputting a signal indicating obstructive material is within the lumenof the aspiration catheter.

Any of these methods may include analyzing the impedance signal todetect a change in impedance indicating obstructive material is within aproximity of the first internal electrical impedance sensor. Applyingthe variable current may comprise applying variable current having afrequency of 50 kHz or more. Any of these methods may includedetermining if the obstructive material is clogged within the lumenbased on the impedance signal.

In any of these methods applying the variable current between two ormore electrodes may comprise applying a plurality of frequencies toobtain an impedance spectrum, wherein detecting the obstructive materialwithin the lumen comprises using the impedance spectrum to detect theobstructive material. Any of these methods may include determining arate of movement of the obstructive material within the lumen. Themethods may include applying the same or a different variable currentbetween two or more electrodes of a second internal electrical impedancesensor within the lumen of the aspiration catheter and detecting theobstructive material within the lumen of the aspiration catheter nearthe second internal electrical impedance sensor.

Also described herein are apparatuses that are configured to determinethe identify of a material at the aspiration opening using electricalimpedance. For example, the methods and apparatuses described herein mayinclude one or more sensors at the aspiration opening (aspirationopening sensors) to distinguish between clot and vessel wall. In theseapparatuses and methods a force (e.g., suction) may be applied betweenthe material and aspiration opening at the distal end (tip) region. Ingeneral, it may be difficult to distinguish between clot and vesselwall, particularly when initially applying suction, during which timethe material may block the aspiration opening in to the suction lumen,and it may be unclear if it is blocked because the apparatus is againstthe vessel wall or is against a large clot. Generally this may lead tolong delays while the physician waits to see if the material will becleared by the suction (or by an increase in suction). Thus, it would bebeneficial to more quickly distinguish between clot material and wallmaterial more accurate and quickly. Further, it may be particularlybeneficial to provide an analysis technique that isolates the material(clot or wall) from blood and/or from situations in which both wall andvessel contact the aspiration opening, which may give an ambiguousresult. As described herein, the use of impedance sensing electrodes atthe distal aspiration opening (or just recessed relative to the distalaspiration opening) may permit the rapid identification of either wallor clot material.

For example, described herein are apparatuses comprising: a flexibleelongate body having a suction lumen extending therethrough; anaspiration opening into the suction lumen at a distal end region of theflexible elongate body; an aspiration opening sensor comprising two ormore electrodes positioned at a rim of the aspiration opening; and acontroller coupled to the aspiration opening sensor and configured todistinguish between clot and vessel wall based on an impedance signalbetween the two or more electrodes when a force is applied to theflexible elongate body or through the suction lumen. The controller maybe configured to distinguish between clot and vessel wall when anegative pressure within the suction lumen exceeds a threshold. Thecontroller may be configured to distinguish between clot and vessel wallwhen a mechanical force is applied against the aspiration opening abovea threshold.

In some examples the aspiration opening is on a tapered side of thedistal end region of the flexible elongate body. The two or moreelectrodes of the aspiration opening sensor may be recessed from therim. The two or more electrodes of the aspiration opening sensor may berecessed into the suction lumen at the rim. The two or more electrodesof the aspiration opening sensor may be spaced equally apparat from eachother on the rim of the aspiration opening. The two or more electrodesof the aspiration opening sensor may be positioned opposite each otheracross the aspiration opening. In some examples the two or moreelectrodes of the aspiration opening sensor are positioned opposite eachother across the aspiration opening at a region of minimum diameter.

Any of these apparatuses may include a plurality of smallerflow-modifying openings into the suction lumen positioned adjacent tothe aspiration opening, and a second impedance sensor comprising two ormore electrodes positioned adjacent to the plurality of smallerflow-modifying openings.

An apparatus may include: a flexible elongate body having a suctionlumen extending therethrough; an aspiration opening into the suctionlumen at a distal end region of the flexible elongate body; anaspiration opening sensor comprising two or more electrodes positionedat a rim of the aspiration opening; and a controller coupled to theaspiration opening sensor and configured to distinguish between clot andvessel wall based on an impedance signal between the two or moreelectrodes when a negative pressure applied through the suction lumenexceeds a threshold.

Also described herein are apparatuses comprising: a flexible elongatebody having a suction lumen extending therethrough; an aspirationopening into the suction lumen at a distal end region of the flexibleelongate body; an aspiration opening sensor comprising two or moreelectrodes positioned at a rim of the aspiration opening; a proximalsuction port in communication with the suction lumen; and one or moreconnectors at a proximal end region of the flexible elongate body,wherein the one or more connectors are in electrical communication withthe two or more electrodes of the aspiration opening sensor, furtherwherein the one or more connectors are configured to couple to acontroller to provide electrical impedance input to distinguish betweenclot and vessel wall when a force is applied to the flexible elongatebody or through the suction lumen.

The apparatus may include a second set of two or more electrodes withinthe suction lumen proximal to the aspiration opening sensor, further theone or more connectors may be in electrical communication with thesecond set of two or more electrodes to provide differential electricalimpedance input from the two or more electrodes of the aspirationopening sensor to distinguish between clot and vessel wall when a forceis applied to the flexible elongate body or through the suction lumen.

The aspiration opening is angled. The two or more electrodes of theaspiration opening sensor may be recessed from the rim. The two or moreelectrodes of the aspiration opening sensor may be recessed into thesuction lumen at the rim. The two or more electrodes of the aspirationopening sensor may be spaced equally apart from each other on the rim ofthe aspiration opening. The two or more electrodes of the aspirationopening sensor may be positioned opposite each other across theaspiration opening. The two or more electrodes of the aspiration openingsensor may be positioned opposite each other across the aspirationopening at a region of minimum diameter.

Any of these apparatuses may include a plurality of smallerflow-modifying openings into the suction lumen positioned adjacent tothe aspiration opening, and/or a second impedance sensor comprising twoor more electrodes positioned adjacent to the plurality of smallerflow-modifying openings.

Also described herein are methods of distinguishing a blood clot from avessel wall, the method comprising: applying suction through a lumen ofa flexible elongate catheter, wherein the flexible elongate cathetercomprises an aspiration opening at a distal end region and two or moreelectrodes at or adjacent to the aspiration opening; and determining,when a force at the aspiration opening exceeds a threshold value, if theaspiration opening is engaged with a blood clot or with the vessel wallbased on an impedance measured from the two or more electrodes at oradjacent to the aspiration opening.

The force at the aspiration opening may include a negative pressurewithin the lumen. Any of these methods may include emitting an alertindicating if the aspiration opening is engaged with one or both ofblood clot and vessel wall.

The methods described herein may include applying alternating currenthaving a frequency of between about 1 kHz and 1 MHz. For example, thealternating current may have a frequency of between about 10 kHz and 100kHz.

The methods described herein may include delaying the step ofdetermining if the aspiration opening is engaged with a blood clot orwith the vessel wall for a delay period after the force exceeds thethreshold value. In any of these methods, determining if the aspirationopening is engaged with blood clot or with vessel wall may be based on adifference in impedance measurements from the two or more electrodes ator adjacent to the aspiration opening and a second set of two or moreelectrodes positioned proximally from the two or more electrodes at oradjacent to the aspiration opening. Any of these methods may includeadjusting suction through the lumen based on the impedance measured fromthe two or more electrodes at or adjacent to the aspiration opening.

Also described herein are methods of removing an obstructive materialfrom a vessel, the method comprising: applying negative pressure to asuction lumen of a flexible elongate catheter having an aspirationopening and two or more electrodes at or adjacent to the aspirationopening; taking an impedance measurement from the two or more electrodesat or adjacent to the aspiration opening while applying the negativepressure; and adjusting the negative pressure based on the impedancemeasurement taken.

In general, the methods and apparatuses described herein may track clotmaterial within the lumen of the catheter using impedance sensing.Tracking material may include confirming that the clot material iswithin (or has left) the suction lumen, determining the rate of flow ofthe material through the suction lumen, estimating a volume or amount ofclot material removed through the suction lumen, or the like.

For example, an apparatus may include: a flexible elongate body having asuction lumen extending therethrough; a first pair of electrodes withinthe suction lumen; a second pair of electrodes proximal to the firstpair of electrodes; and a controller coupled to the first pair ofelectrodes and the second pair of electrodes and configured to track aclot material within the suction lumen based on electrical impedancesignals from the first pair of electrodes and the second pair ofelectrodes.

The first pair of electrodes may comprise a pair of annular electrodesextending at least partially radially around the suction lumen. The pairof annular electrodes may comprise ring electrodes extending radiallyaround the suction lumen. The pair of annular electrodes may comprisehelical electrodes. The pair of annular electrodes may be separated fromeach other by between 0.1 and 20 mm. The pair of annular electrodes mayeach extend 30 degrees or more radially around the suction lumen. Thefirst pair of electrodes and the second pair of electrodes may comprisea quad detector. For example, the first pair of electrodes may be spacedfrom the second pair of electrodes by between 0.1 and 20 mm along adistal-to-proximal length of the suction lumen.

Any of these apparatuses may include an alternating electrical powersource coupled to the first pair of electrodes and configured to apply avariable voltage. The controller may be further configured to determinea size of the clot material based on electrical impedance signals fromthe first pair of electrodes and the second pair of electrodes. Thecontroller may be configured to determine a rate of flow of the clotmaterial within the suction lumen based on electrical impedance signalsfrom the first pair of electrodes and the second pair of electrodes.

The controller may be configured to distinguish between clot materialand vessel wall based on electrical impedance signals from the firstpair of electrodes and the second pair of electrodes. For example, thecontroller may be further configured to modulate suction through thesuction lumen based at least in part on an electrical impedance signalfrom the first pair of electrodes.

An apparatus may include: a flexible elongate body having a suctionlumen extending therethrough; an aspiration opening into the suctionlumen at a distal end region of the flexible elongate body; a first pairof electrodes within the suction lumen and extending at least partiallyaround the suction lumen; a second pair of electrodes proximal to thefirst pair of electrodes with the suction lumen and extending at leastpartially around the suction lumen; a proximal suction port incommunication with the suction lumen; and one or more connectors at aproximal end region of the flexible elongate body, wherein the one ormore connectors are in electrical communication with the first pair ofelectrodes and the second pair of electrodes, further wherein the one ormore connectors are configured to couple to a controller to provideelectrical impedance input to track a clot material within the suctionlumen based on electrical impedance signals from the first pair ofelectrodes and the second pair of electrodes. The first pair ofelectrodes and the second pair of electrodes may comprise a quaddetector comprising two pairs of electrodes. The first pair ofelectrodes and the second pair of electrodes may be spaced apart fromeach other by between 0.1 and 20 mm along a distal-to-proximal length ofthe suction lumen.

A method of tracking a clot material within a suction lumen of acatheter may include: receiving a first impedance signal from a firstpair of electrodes within the suction lumen; receiving a secondimpedance signal from a second pair of electrodes within the suctionlumen; and estimating one or more of a rate of flow of a clot materialand a volume of clot material from the first impedance signal and thesecond impedance signal. Any of these methods may include outputting theone or more of the rate of flow of the clot material and the volume ofthe clot material. The method may include detecting a blockage of thecatheter based on the first impedance signal and the second impedancesignal. Any of these methods may include adjusting a suction through thesuction lumen based on the first impedance signal and the secondimpedance signal.

Estimating the one or more of the rate of flow of a clot material andthe volume of clot material may comprise correlating the first impedancesignal and the second impedance signal. Estimating the one or more ofthe rate of flow of a clot material and the volume of clot material maycomprise determining a time difference between the correlation of thefirst impedance signal and the second impedance signal.

All of the methods and apparatuses described herein, in any combination,are herein contemplated and can be used to achieve the benefits asdescribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the features and advantages of the methods andapparatuses described herein will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,and the accompanying drawings of which:

FIG. 1A schematically illustrates one example of an apparatus forcontrolling a suction catheter.

FIG. 1B is an end view of one example of a suction catheter forming partof the apparatus of FIG. 1A.

FIG. 1C schematically illustrates another example of an apparatus forcontrolling a suction catheter.

FIG. 1D shows an end view of the suction catheter portion of theapparatus of FIG. 1C.

FIG. 2 is an end view of one example of an elongated shaft of a suctioncatheter as described herein.

FIG. 3 is an end view of an example of an elongated shaft of a suctioncatheter including a monopolar impedance sensor on the distal end of thecatheter (showing a single electrode on the distal face of the suctioncatheter).

FIG. 4 is an end view of an example of an elongated shaft of a suctioncatheter including a bipolar impedance sensor on the distal end of thesuction catheter (including two proximal electrodes on the distalportion of the catheter).

FIG. 5 is an end view an example of an elongated shaft of a suctioncatheter including a several electrodes situated circumferentially aboutthe opening of the distal portion of the suction catheter (radiallydistant from the center and outer limit of the distal portion of thecatheter)

FIG. 6 is an end view of an example of an elongated shaft of a suctioncatheter including a bipolar impedance sensor on the suction catheter(showing the same circumferential distribution as in FIG. 4 . with eachmonopolar electrode being replaced with proximal pairs of bipolarelectrodes).

FIG. 7 is an end view an example of an elongated shaft of a suctioncatheter including a bipolar impedance sensor on the distal portion ofthe suction catheter (including a single electrode pair with eachelectrode situated on opposite semicircles of the distal portion of thecatheter and radially distal to both the center and outer edge of thedistal portion).

FIG. 8 is an end view an example of an elongated shaft of a suctioncatheter including a bipolar impedance sensor on the distal portion ofthe suction catheter (including two electrode pairs with each electrodein each pair situated on opposite semicircles of the distal portion ofthe suction catheter and with each pair rotated at an angle of 90°relative to one another about the center of the distal portion).

FIG. 9 is an end view an example of an elongated shaft of a suctioncatheter including a monopolar impedance sensor on an impermeable wallportion of the suction catheter (including a single monopolar electrodeexternally fitted to the impermeable wall enclosing an inner region).

FIG. 10 is an end view an example of an elongated shaft of a suctioncatheter including bipolar impedance sensor on a wall portion of thesuction catheter (showing a single pair of proximal electrodesexternally fitted to the wall enclosing an inner region.

FIG. 11 is an end view an example of an elongated shaft of a suctioncatheter including a monopolar impedance sensor on the wall portion ofthe suction catheter (including several monopolar electrodes fittedcircumferentially and externally on the wall enclosing an inner region).

FIG. 12 is an end view an example of an elongated shaft of a suctioncatheter including a bipolar impedance sensor on the wall portion of thesuction catheter (showing several proximal pairs of bipolar electrodesfitted circumferentially and externally on the wall enclosing an innerregion).

FIG. 13 is an end view an example of an elongated shaft of a suctioncatheter including a bipolar impedance sensor on the wall portion of thesuction catheter (showing a single distal pair of bipolar electrodessituated opposite one another, circumferentially, and externally on thewall enclosing an inner region).

FIG. 14 schematically illustrate an example of an apparatus including asuction catheter in which suction is controlled, at least in part, by acontroller receiving input from one or more sensors on a distal-facingportion of the catheter and one or more sensors within the lumen of thesuction catheter for sensing clot material at or near these regions.

FIG. 15 schematically illustrate an example of an apparatus including asuction catheter and a macerator that are each controlled by acontroller receiving input from multiple sensors.

FIG. 16 schematically illustrates an example of an apparatus including asuction catheter and a macerator that are each controlled by acontroller receiving input from multiple sensors; the example shown inFIG. 16 also includes positive pressure as well as negative pressure.

FIGS. 17A-17E illustrate operation of an apparatus similar to that shownin FIG. 16 removing clot material from a blood vessel with minimal bloodloss.

FIGS. 18A-18E illustrate operation of an apparatus similar to that shownin FIG. 16 , including a suction catheter, removing clot material from ablood vessel.

FIG. 19 is one example of a state diagram for an apparatus as describedherein.

FIG. 20 illustrates one example of a macerator that may be used as partof any of the apparatuses described herein.

FIG. 21 is an example of a macerator that may be used as part of any ofthe apparatuses described herein.

FIG. 22 is an example of a macerator that may be used as part of any ofthe apparatuses described herein.

FIG. 23 is an example of a macerator that may be used as part of any ofthe apparatuses described herein.

FIG. 24 is another example of a macerator that may be used as part ofany of the apparatuses described herein.

FIG. 25 illustrates one example of a suction catheter as describedherein.

FIG. 26 illustrate one example of a method of detecting a clot material.

FIG. 27A illustrates one example of an apparatus for removing clotmaterial, including a macerator.

FIG. 27B illustrates an example of an apparatus for removing clotmaterial, including a macerator.

FIG. 28 illustrates an example of a method of detecting clot materialusing an optical sensor.

FIGS. 29A-29B illustrate an example of an apparatus for removing clotmaterial using an optical sensor to detect clot material. FIG. 29A showsa section through a distal end region of the apparatus. FIG. 29B shows alongitudinal section through the apparatus.

FIGS. 30A-30C illustrate a method of operating an apparatus for removingclot material using an optical sensor.

FIGS. 31A-31B illustrate examples of apparatuses for removing clotmaterial. FIG. 31A shows an apparatus including an optical sensor. FIG.31B shows an apparatus including a contact sensor based on opticaldetection of contact.

FIGS. 31C-31D show examples of optical sensors.

FIG. 32 schematically illustrates one example of an optical sensor.

FIG. 33 schematically illustrates one example of an apparatus forremoving clot material including an optical sensor.

FIG. 34 illustrates an example of a method of detecting clot materialincluding detecting a contact pressure.

FIGS. 35A-35B illustrate an example of an apparatus for removing clotmaterial. FIG. 35A shows an apparatus including a contact senor. FIG.35A shows the distal end region of the apparatus; FIG. 35B shows anexample of a proximal end region of the apparatus.

FIG. 35C shows another example of an apparatus for removing clotmaterial including a contact sensor.

FIG. 36 schematically illustrates one example of an optical contactsensor including an emitting fiber and a sensing fiber.

FIGS. 37A-37D illustrate operation of an apparatus for removing clotmaterial including a contact sensor.

FIGS. 38A-38B illustrate examples of extraction entrances of apparatusesincluding sensors for detecting material entering the extraction chamberregion of the apparatus.

FIGS. 39A-39E illustrate a method of distinguishing clot material fromvessel lumen using an apparatus as described herein.

FIG. 40 illustrates an example of a method of detecting clot materialusing suction and confirming clot material is drawn into the extractionchamber of the apparatus.

FIG. 41 illustrates one example of a thrombectomy apparatus that detectsclot material within the extraction chamber region of the apparatus tocontrol operation of the apparatus.

FIG. 42 illustrates another example of a thrombectomy apparatusconfigured to detect material within the extraction chamber (e.g., usingsuction) by monitoring the macerator and/or pressure within theextraction chamber.

FIG. 43 schematically illustrates an example of a macerator as describedherein.

FIG. 44 illustrates an example of a method of controlling clot removingusing an apparatus configured to detect opening of an aperture through acover over the extraction chamber.

FIG. 45 schematically illustrates one example of a thrombectomyapparatus configured to detect clot material and distinguish betweenclot material and wall material including sensors for sensing opening ofan aperture into a clot extraction region of the apparatus.

FIGS. 46A-46B illustrate the operation of a thrombectomy apparatusconfigured to detect opening of an aperture into an extraction chamber.

FIG. 47 illustrates one example of a thrombectomy apparatus as describedherein.

FIGS. 48A-48C show examples of a thrombectomy apparatus including anobstruction sensor configured as a deflectable member as describedherein. FIGS. 48B-48C shows the apparatus with clot within theextraction chamber of the apparatus.

FIG. 49 illustrates one example of an apparatus (e.g., a thrombectomyapparatus) including an aspiration catheter configured to include aplurality of deflectable members and a macerator.

FIG. 50 illustrates an example of an apparatus (e.g., a thrombectomyapparatus) including an aspiration catheter including a plurality ofdeflectable member and a macerator.

FIG. 51A schematically illustrates an example of a deflection sensingcircuit for a deflectable member.

FIG. 51B schematically illustrates an example of a deflection sensingcircuit for a deflectable member.

FIG. 52 is a graph illustrating different scenarios for operation of anapparatus using a deflectable member as an obstruction sensor asdescribed herein.

FIG. 53 illustrates an example of a method of controlling clot removingusing an apparatus including one or more deflectable members asdescribed herein.

FIGS. 54A-54C illustrates an example of a deflectable member configuredas a spring element that extends longitudinally (axially) within thesuction lumen to detect clot material. FIG. 54A shows the deflectablemember in a first (undeflected) configuration, while FIG. 54B shows thedeflectable member in a second (deflected) configuration, such as whenclot material is trapped within the distal end region of the suctionlumen. FIG. 54C shows an example of a graph showing the change inelectrical properties of the deflectable member in the deflectedconfiguration(s).

FIG. 55 schematically illustrates an example of a deflectable memberconfigured as an optical, shape-sensing bend sensor.

FIG. 56 schematically illustrates an example of a deflectable memberconfigured as a resistive sensor in which the resistance changes as thedeflectable member bends.

FIG. 57 schematically illustrates an example of an aspiration catheterincluding a deflectable member and a detection sensor (circuit) asdescribed herein.

FIG. 58A schematically illustrates an example of an aspiration catheterincluding a general impedance sensor similar to that described above.

FIG. 58B schematically illustrates an example of an aspiration catheterincluding one variation of an impedance sensor.

FIG. 58C schematically illustrates an example of an aspiration catheterincluding a second variation of an impedance sensor.

FIGS. 59A-59B show one example of a suction catheter apparatus asdescribed herein, including sensors (e.g., impedance sensors) within thelumen to detect and/or track clot material within the lumen. FIG. 59Bshows a cross-section through a distal end region of the catheter.

FIG. 60 schematically illustrates an example of a suction catheterincluding an internal distal electrical (e.g., impedance) sensor.

FIG. 61 schematically illustrates an example of a pair of ringelectrodes that may be used as internal electrodes for any of theelectrical sensors described herein.

FIG. 62 schematically illustrates an example of a suction catheterincluding an internal distal electrical (e.g., impedance) sensor and aninternal proximal electrical (e.g., impedance) sensor, not drawn toscale.

FIG. 63A schematically illustrates an example of a pair of annular ringelectrodes similar to those of FIG. 61 .

FIG. 63B schematically illustrates an example of a pair of ringelectrodes that extend only partially around the annuls of the innerlumen of a suction electrode.

FIG. 63C schematically illustrates an example of a pair of helicalelectrodes that may be functionally equivalent to the ring electrodesshown in FIGS. 63A-63B.

FIG. 64 is a graph illustrating impedance data over time from theoperation of a suction catheter including an electrical sensor at adistal end and an electrical sensor at a distal end of the catheter, asthe suction catheter removes clot material.

FIG. 65 schematically illustrates an example of an apparatus for sensingclot material including a catheter (not shown to scale) with a suctionlumen and internal electrical impedance sensors as well as a pair ofimpedance sensors at the distal aspiration opening.

FIG. 66 is a graph showing impedance signals over time from each of thethree sets of internal impedance sensors (e.g., pairs of electrodes)within the lumen of an apparatus such as the apparatus shown in FIG. 65.

FIG. 67 is schematic example of an apparatus including an aspirationopening sensor having two electrodes positioned at a rim of theaspiration opening of an aspiration catheter.

FIG. 68 schematically illustrates an example of an apparatus includingan aspiration opening sensor (with two electrodes positioned at a rim ofthe aspiration opening) and a set of internal impedance sensors slightlyproximal to the aspiration opening sensor within the suction lumen.

FIG. 69A is an example of a schematic circuit of an impedance sensor.

FIG. 69B illustrates a trace of an example of an alternating currentthat may be applied for sensing impedance.

FIG. 70 schematically illustrates an example of an apparatus includingan aspiration opening sensor comprising a piezoelectric transducer(e.g., shown as a pair of piezoelectric transducers).

FIG. 71 schematically illustrates an example of an apparatus includingan aspiration opening sensor comprising an optical sensor as describedherein.

FIG. 72 schematically illustrates an example of an apparatus includingan aspiration opening sensor comprising an electromagnetic sensor asdescribed herein.

FIG. 73 schematically illustrates an example of an apparatus includingan aspiration opening sensor comprising an inductive sensor.

FIG. 74 schematically illustrates an example of an apparatus includingan aspiration opening sensor comprising a thermal sensor.

FIG. 75 schematically illustrates an example of an apparatus includingan aspiration opening sensor comprising a mechanical sensor.

FIG. 76 illustrates an example of a quad detector comprising fourelectrodes (two electrode pairs) separated by a predetermined distancewithin a suction lumen of a catheter as described herein.

FIGS. 77A-77C illustrate examples of impedance signals measured using afirst configuration of an aspiration opening sensor comprising a pair ofelectrodes measuring electrical impedance at different frequencies whenforce is applied (e.g., by applying suction) against different materials(e.g., vena cava/wall or clot material). In FIG. 77A the percentage ofchange in the impedance compared to the impedance of blood is shownrelative to vena cava/wall (on left of each pair per frequencies) andclot (on right of each pair per frequency). FIGS. 77B-77C show theimpedance of the aspiration opening sensor for blood (left), venacava/wall (middle) or clot material (right) at different frequencies(120 Hz, 1 kHz, 10 kHz, 100 kHz, and 1 MHz) in different conditions.

FIGS. 78A-78C illustrate examples of impedance signals measured using anaspiration opening sensor comprising a pair of electrodes measuringelectrical impedance at different frequencies when force is applied(e.g., by applying suction) against different materials (e.g., venacava/wall or clot material).

FIGS. 79A and 79B illustrate examples of internal impedance sensors.

FIG. 80 is an example of an internal impedance sensor having an internalring.

FIGS. 81A and 81B are examples of internal impedance sensors configuredas a quad detectors.

FIG. 82 illustrate one example of a estimates of clot volume usingimpedance measurements taken from various configurations of internalimpedance sensors (similar to those shown in FIGS. 79A-79B, 80 and81A-81B.

FIG. 83 is a graph showing an example of impedance measurements overtime from various internal impedance sensors tracking clot materialmoving through the suction lumen of the apparatus, in which the clotmaterial remains together.

FIG. 84 is a graph showing an example of impedance measurements overtime from various internal impedance sensors tracking clot materialmoving through the suction lumen of the apparatus, in which the clotmaterial breaks up as it moves through the suction lumen.

FIG. 85 illustrates one example of an apparatus for aspiration material,confirming/detecting material at the aspiration opening, and trackingmaterial within the suction lumen of the apparatus.

DETAILED DESCRIPTION

In general, described herein are methods and apparatuses for removingclot material from a blood vessel. These methods and apparatuses may beparticularly well suited for removing clot material while minimizingblood loss. These methods and apparatuses may be used to track clotwithin and/or removed by the suction catheter, including (but notlimited to) confirming clot has been removed, quantifying the amount ofclot removed, estimating and/or quantifying the rate of clot removaland/or determining and identifying clogging of the suction catheter.Further, these methods and apparatuses may allow more precise control ofsuction and/or maceration of clot and may help automate (orsemi-automate) clot removal.

Any of the methods and apparatuses described herein may use one or moresensing modalities for detecting the presence and/or for detecting theproximity of, clot material, and in particular detecting the presenceand/or proximity of clot material relative to the distal end opening ofa suction catheter and within the suction catheter. These methods andapparatuses may use any appropriate type (e.g., mode) of sensor,including, e.g., electrical property (e.g., impedance, such asbioimpedance, bioimpedance spectroscopy, etc.), light (e.g., color),and/or ultrasound. Other types of sensors may also be used. The one ormore sensors may be positioned at the distal end (e.g., distal end face)of the catheter, and/or may be present within the lumen of the suctioncatheter, and/or on the macerator. In some examples the sensors may beconfigured as deflection sensors that mechanically sense deflection of adeflectable member due to clot material contacting the deflectablemember. In some examples the sensors may extend radially around thelumen of the suction catheter at least partially around thecircumference (e.g., between 30-360 degrees, between 40-350 degrees,between 60-350 degrees, between 90-360 degrees, between 45-360 degrees,etc.).

Thus, the apparatuses and methods described herein may assist a user(e.g., doctor, surgeon, nurse, technician, etc.) in locating andengaging with thrombus to prevent unnecessary aspiration of whole bloodor surrounding structures such as a vessel wall or a valve. Theseapparatuses may provide improved spatial awareness of the distal end ofthe suction catheter and/or other regions of the suction catheter orsuction catheter lumen. Better spatial awareness at the treatment siteat the distal end of the suction catheter can be advantageous during athrombectomy procedure, for example, as it allows the user to establishproper engagement with clot material before beginning aspiration, whileperforming aspiration and at the end of aspiration, and thus reducesblood loss during the procedure.

The apparatuses described herein may generally include a suctioncatheter, which may include one or more sensors on the distal end of thesuction catheter and may include or may be used with a source of suction(negative pressure). The apparatus may also include, either as a part ofthe controller or separate from the controller, a suction regulator thatmay include valves for modulating the source of suction. In someexamples the apparatus may also include a source of positive pressureand the controller may also regulate the operation of the source ofpositive pressure.

For example, FIG. 1A schematically illustrates one example of anapparatus including suction catheter 103 as described herein. FIG. 1Aincludes an elongate, and flexible suction catheter (not shown to scale)103. The suction catheter may be formed of any appropriate material andmay include a central (suction) lumen and a distal end opening. Thesuction catheter may be formed of any appropriate material. One or more(e.g., two are shown in FIG. 1A) sensors 105, 105′ are included at thedistal end face of the suction catheter. The sensors are connected to acontroller 104 that may receive and process data from the sensors. Oneor more sensors (internal sensor or set of sensors) 106 may also bepresent within the lumen of the distal end region of the suctioncatheter and/or within more proximal regions. All of the sensors mayprovide data input to the controller 104. The connection may be wiredthrough the suction catheter and may connect via one or more connectorsto the controller.

The controller may control the suction applied through the suctioncatheter by either controlling a pump and/or suction reservoir 109directly or by regulating the pressure from the vacuum pump andreservoir indirectly via a pressure modulator 111 that may include oneor more valves, manifolds, etc. to control the pressure within thesuction catheter.

FIG. 1B shows an end view of the suction catheter of FIG. 1A, showingthe distal-facing sensors 105, 105′ on the outer edge of the suctioncatheter, as well as the suction lumen 120 of the catheter. In FIG. 1B,a pair of internal sensors 106 from within the lumen are shown; inpractice the sensors may be flush with the inside wall of the catheter,and/or may be recessed into the catheter wall.

The controller may include control circuitry for receiving and/orprocessing data from the sensors, and for transmitting control signalsto the pump modulator 111 or pump 109. For example, the controller mayinclude one or more processors, timing circuitry, a memory, and thelike. In some examples the controller may also include one or moreoutputs, such as a display, a speaker, etc. The controller may connectwireless or via a cable or wire to a remote processor, or computer(e.g., laptop, desktop, etc.). The controller may indicate via outputwhen clot material is present in front of or in the lumen of the suctioncatheter, and/or when suction is being applied.

Any of these apparatuses may include a macerator to help break up clotmaterial for easier removal from the vessel (and through the lumen ofthe suction catheter). For example, FIGS. 1C and 1D schematicallyillustrate an example of an apparatus including a macerator 129 that maybe positioned (including removably and/or adjustably positioned) withinthe lumen of the suction catheter 103, as shown. The apparatus shown inFIG. 1C is configured as a system that also includes the controller 104receiving input from sensor(s) 105, 105′ at the distal end face of thesuction catheter as well as sensors 106 within the catheter. As shown inFIG. 1C, the second set of sensors shown may also include one or moresensors 143 on the macerator 129. In FIG. 1C, the macerator includes oneor more windows through an elongate and flexible macerator body thatexpose a cutting member 133 (shown as a rotating thread in FIG. 1C). Anyappropriate cutting member may be used, including wires, blades, etc.The macerator may be actuated by a drive 131 (macerator driver) thatrotates a flexible drive shaft 133 (macerator drive shaft). As will bedescribed in greater detail below, the controller 104 may controlactuation of the macerator in addition to or instead of controllingsuction through the suction catheter.

FIG. 1D shows a distal end view of the suction catheter of FIG. 1C. Asin FIG. 1B, the catheter may include one or more distal-facing sensors(e.g., impedance electrodes in some examples). In FIG. 1D the macerator129 is shown in the suction lumen. In this example the sensors withinthe lumen at or near the distal end portion. FIGS. 1A-1D illustrateexamples of suction catheters including sensors. Different types, sizesand sensitivity of sensors may be used.

FIG. 2 shows a schematic of a distal end region of a suction catheter.In FIG. 2 the distal end face of the catheter is covered by a membrane(e.g., a flexible and deformable polymeric (e.g., silicone) cover 2. Thesensors 5, which in this example and in FIGS. 3-12 , show the locationsand orientation of these sensors on the suction catheter. The suctioncatheter includes an inner wall (not visible) and an outer wall 4. Theflexible cover may include a small opening 3 that may enlarge to allowclot material to pass. In FIG. 2 , a pair of sensors 5 are included andmay provide input, either continuously or discretely.

FIGS. 3-13 illustrate alternative examples of the distal end of asuction catheter including sensors arranged on the outer surface(including the distal-facing end) and the inner lumen. In all of FIG.3-13 , the distal end of the suction catheter 4 includes a cover 2 thatmay be impermeable to blood, but which may include an opening 3 (e.g., ahole, slit(s), etc.), that may expand when clot is drawn into the lumenby suction. This may limit blood loss into the suction catheter bothbefore and during the application of suction upon detection of clotmaterial, as will be described in greater detail below. In FIG. 3 , asingle sensor 1 is shown. This example may be, e.g., a monopolarbioimpedance sensor. FIG. 4 shows an example in which a bipolarbioimpedance sensor 8 is included on a distal face of the cover. In FIG.5 a plurality of sensors (e.g., shown in this example as eight sensors)are arranged around the cover, spaced equidistantly. In FIG. 5 thesensors 1 are shown as monopolar bioimpedance sensors (though othersensor types may be used), while in FIG. 6 the sensors 8 are bipolarbioimpedance sensors. In FIG. 7 a pair of radially spaced-apartelectrodes 8 (forming a larger bipolar bioimpedance sensor) are shown.FIG. 8 shows two pairs of radially spaced-apart bipolar bioimpedancesensors 8 (either opposite electrodes or adjacent electrodes may be usedas a bipolar pair, or partner electrodes may be switched between thesepairs).

FIGS. 9-13 illustrate examples in which the distal end region of thesuction catheter includes one or more sensors within the lumen of thedistal end region of the suction catheter. In FIG. 9 , a single sensor 1is shown within the lumen of the catheter. The sensor may be anelectrical (e.g., bioimpedance sensor, which may be monopolar orbipolar). For example, FIG. 10 illustrates an example of a bipolar pairof electrodes forming a bioimpedance sensor 8 within the lumen of thedistal end of the suction catheter. FIG. 11 shows an example of asuction catheter in which an annual ring of sensors is arranged withinthe lumen of the distal end of the suction catheter, on a sidewall ofthe lumen. The annular ring or rings (longitudinally arranged) ofsensors may be continuous or discrete; for example, an annual ring ofelectrodes may be electrically connected to each other to form a singleelectrical sensor having multiple contact points, as shown in FIGS. 11and 12 . These sensors may be monopolar or bipolar bioimpedance sensors8, for example, as shown in FIG. 12 . FIG. 13 shows an example in whicha bipolar bioimpedance sensor is arranged with either electrode onopposite sides of the lumen of the suction catheter.

For simplicity, FIGS. 9-13 illustrate examples in which only a fewsensors are show, arranged within the distal end region of the suctioncatheter. In some examples, a plurality of sensors may be arranged alongthe length of the lumen extending proximally, allowing tracking of clotmaterial as it passes through the lumen.

Although FIGS. 9-13 show only the sensors within the lumen of the distalend of the suction catheter, in any of these examples one or moresensor(s), including bioimpedance sensors may be positioned on thedistal-facing end of the suction catheter (as shown in FIGS. 3-8 ). Insome of these examples one or more sensors for detecting clot materialmay be positioned proximally along the side length of the outside of thedistal end of the suction catheter, which may be useful to indicate whenclot material is to the side of the suction catheter.

As mentioned, any appropriate sensor may be used, including but notlimited to impedance (e.g., bioimpedance) sensors. One example of abioimpedance sensor (e.g., electrode) that may be used with the methodsand apparatuses described herein is described in Lei et. al., 2013. Forexample, a bioimpedance sensor may have an electrode spacing ofapproximately 1.8 mm for bipolar configurations and a titanium aluminumalloy construction with a 1 mm PDMS coating is associated with allimpedance values and thresholds mentioned herein. Other bioimpedancesensors may be used in any of the methods and apparatuses describedherein.

As mentioned, the apparatus can include a suction catheter having anelongated shaft including a lumen, a negative pressure source configuredto be fluidly coupled to the lumen of the suction catheter, and acontroller. The elongated shaft may be flexible and may include aproximal portion configured to be extracorporeally positioned duringtreatment and a distal portion configured to be intravascularlypositioned proximate clot material at a treatment site within a bloodvessel lumen, such as the lumen of a pulmonary blood vessel or otherblood vessel. The suction catheter may include one or more sensors(“sensing devices”) configured to sense and/or detect clot material. Thesensor(s) can be electrically coupled to the controller such thatmeasurements obtained by the sensor(s) can be processed by thecontroller. In some examples, the controller can be coupled to thenegative pressure source and/or a connection between the negativepressure source (e.g., pressure modulator) and the shaft of the suctioncatheter so that the controller can control the timing (and in somecases level) of the aspiration applied through the shaft.

Returning to FIG. 1A, the sensor may include a plurality of sensingelements (in some examples electrodes, ultrasound transducers, opticaltransducers, fiber optics, etc.) at a distal end region of the elongatedshaft. The sensing elements can be, for example, one or more electrodes.Any number of sensing elements can be used (e.g., one, two, three, four,etc.) or compound sensing elements (e.g., pairs of electrodes, etc.).The sensing elements can be positioned at the distal end portion of theelongated shaft such that the sensing elements have unobstructed accessto the space distal of the elongated shaft and thus can contact and/oraccurately sense clot material disposed in the vessel lumen distal tothe shaft, including in contact with the distal end of the shaft ornearby the distal end of the shaft (e.g., within 1 mm, 2 mm, 3 mm, 4 mm,5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 1 cm, etc.). For example, as shown in theend view of FIG. 1B, the sensing elements can be positioned at thedistal-facing portion of the tubular sidewall that forms the elongatedshaft of the suction catheter. This may be true both in suctioncatheters including a distal cover (e.g., an elastically deformablecover) and suction catheters that do not have a distal cover. In thoseexamples where the system includes a distal cover (for example as shownin FIG. 2 ), the sensing elements can be positioned anywhere along thesurface of the cover. The sensing elements can be configured to senseproximity of the tip of the elongate shaft of the suction catheter toclot material (e.g., thrombus, embolus, etc.) in blood vessels, whichmay be used to in combination with existing positioning systems andmethods such as fluoroscopy and in controlling aspiration (suction)through the suction catheter, either manually or automatically. This mayaid in reducing the volume of blood aspirated during clot removal. Thesensing mechanisms may provide signals and indications which enable theuser to discriminate between clot material, whole blood, vessel walls,and other surrounding structures in the treatment zone. In someexamples, the apparatus may initially attain partial engagement with aclot material. A sensor may be a sensor array that may include severalelectrodes (e.g., impedance sensors) or optical sensorscircumferentially arranged about the distal face of a funnel or tubularopening into the suction catheter, to provide point-measurements ofproximity to clot material (and in some cases lumen wall) and enable thepractitioner to make directional corrections of the device within theblood vessel to more completely engage with clot material. In someexamples the distal end of the suction catheter (e.g., a cylindrical orfunnel-shaped opening) may include one or more ultrasound transducers;the ultrasound transducer(s) may be positioned to achieve spatialawareness to the end of the suction catheter.

The schematic shown in FIGS. 1A and 1C illustrate just one generalconfiguration for several examples of the apparatuses described herein.The sensors shown in these examples as well as the examples shown inFIGS. 2-13 are illustrated as electrical (e.g., impedance) sensors,however similar configurations and/or positions may be used for othersensor types (or combinations of sensor types), including ultrasoundand/or optical sensors. In some examples the sensors may be an impedancesensing elements that include two electrodes in a dipole configurationwhich are connected electrically to the controller and/or other signalprocessing or power components, including sensing, signal processing,and control units.

Optionally, the controller may be connected to one or more valves whichregulate the pathway between the elongated shaft and a source of suction(e.g., a vacuum chamber) and/or in some examples a source of positivepressure (e.g., a pressure chamber). Alternatively, the controller maybe connected directly to the source of suction and/or positive pressure.For example, the controller may control the action (on/off, rate ofpumping, etc.) of the source of suction without an additional valveneeded between the pump (suction and/or positive pressure source(s)) andthe suction catheter.

In operation, the suction catheter may therefore detect, via the one ormore distal-facing sensors (e.g., on the distal end of the suctioncatheter) when the distal tip is in blood or is near or in contact withclot material. For example, while these sensor(s) are in contact withblood, when using a bioimpedance sensor an alternating current passingthrough the blood between pairs of sensing electrodes may see arelatively low impedance, generally across an entire frequency spectrum.This relatively low impedance may be processed and categorized in thesensing and signal processing units within the controller. If theimpedance is low enough to statistically infer the absence of thrombusproximal to the distal opening into the suction catheter, and thecontrol unit may maintain the suction “off” or at a low level, either bydirectly controlling the source of negative pressure or by regulating avalve (to be or remain in a closed state) so that the negative pressuredoes not communicate (or increase) to the suction catheter opening,preventing or limiting blood aspiration therein. As clot materialapproaches the electrodes of the bioimpedance sensor(s), the impedancemay increase and converge to a range of values that indicatecharacteristic impedance (or impedance spectra) of clot material. Thevalue(s) indicative of clot may be distinguished by the controller fromthose that indicate vessel wall or other structures that are not clotmaterial. Once the clot material is in full engagement with the sensors(and therefore the distal end of the suction catheter), the controller,upon verifying that the sensor data indicates clot material, may turn on(or otherwise increase) suction. For example, in some cases (dependingon the construction of the bioimpedance sensors) an impedance value ofapproximately 1,000,000 Ohms and above may indicate to the controllerthat the clot material is near and/or in contact with the distal end ofthe suction catheter. The controller may increase or turn on suctionthrough the suction catheter. In some examples, the system may begin orincrease vacuum pressure once the thrombus makes adequate contact withthe sensors and distal end of the suction catheter to aspirate the clotmaterial. As the clot material is aspirated, the impedance may remainabove the threshold until the clot material all aspirated from the frontof the suction catheter. Importantly, suction of the clot material maybe configured and tracked using the sensors within the lumen of thesuction catheter.

The use of one or more sensors for detecting clot within the lumen ofthe suction catheter is surprisingly effective at regulating suction andaction of the suction catheter, rather than relying on or requiringpressure or flow sensing. Although pressure and/or flow sensing may beused within the suction catheter, the use of one or more sensors thatdirectly detect clot material is more robust and reliable forcontrolling negative pressure and, as will be described in greaterdetail below, for controlling disruption of clot material within thelumen of the suction catheter by controlling maceration within the lumenof the suction catheter.

In some examples the controller may continue to maintain the suction(e.g., at the on state or at a higher state) until both the clotmaterial has been fully aspirated into the suction catheter and untilthe sensor(s) within the lumen of the suction catheter indicate that theclot material has been removed from the distal end region of the suctioncatheter. Once clot material has been removed, for example when usingbioimpedance sensors, the sensed impedance (or impedance spectrum) willdrop back down to the range of impedance values consistent with justblood (e.g., in some examples less than 10,000 Ohms, depending on thefrequency) and the controller will turn off or reduce the suctionthrough the suction catheter (e.g., set one or more valves of a suctionmodulator to a closed state, turn off the suction pump, etc.).

In some examples the suction modulator and/or the source of suction(e.g., pump) may be configured so that the standby/unpowered state is anoff state, to prevent unsafe adverse aspiration in the event of damagedor contaminated sensors. For example, a valve in the suction modulatoror source of suction may be a normally closed solenoid. Anomalydetection (as known in the art) may be implemented in the controller toprevent unintended and/or undesirable application of suction without thepresence of clot material. In general, the controller may includesensing and signal processing for robustly confirming the presence ofclot material from sensor data.

When the apparatus includes bioimpedance sensors, these sensors may beconfigured to include bipolar or monopolar electrodes. Monopolarelectrodes and bipolar electrodes may be used nearly equivalently,however monopolar configurations each electrode may represent anindividual signal and the controller may incorporate these additionalsignals. The respective ranges of sensing may be different for theseelectrodes. In any of these apparatuses, the sensors may be distributedin position, e.g., along the distal portion of the suction catheter, andmay provide data (e.g., impedance values for bioimpedance sensors) fromseparate locations in order to provide spatial information about theclot material relative to the opening into the suction catheter. Thisinformation may be processed by the controller to further threshold thetiming and/or level of suction applied. In some examples, the controllermay establish an impedance threshold for a plurality of (e.g., n)dimensions, based on the number of impedance sensors available(monopolar or bipolar). This multiple-signal configuration could beprocessed in the controller and exported to an external display forproviding the practitioner with additional spatial information about themedia proximal to the distal end of the suction catheter.

In general, as mentioned above, the apparatus may provide output to theuser from the suction, including a visual display (e.g., video), anumeric value (e.g., some indication of impedance at the distal endand/or within the suction catheter), etc.

For example, the apparatus may include bioimpedance sensors that operateas dipole pairs that are located on the surface (such as thedistal-facing surface and/or distal membrane) of a suction catheter. InFIG. 2 , for example, the diploe pairs of the sensor may include twoseparate dipole electrodes 5 situated on opposite halves of the distalmembrane 2 which operate as one dipole pair. In the dipoleconfiguration, AC current passes through local tissue surrounding thedistal membrane and between both electrodes. The effective resistance ofthe tissue in immediate contact with the electrodes is the tissue'simpedance. Different tissue types exhibit different impedancecharacteristics. The real-time indicated impedance can be used todetermine the tissue-type surrounding the distal-face of thethrombectomy device and can be used for guiding the user to the clotmaterial once general proximity is established through non-invasivenavigation such as x-ray fluoroscopy. In this example, when the distalend of the suction catheter (e.g., the distal membrane cover in someexample) is only in contact with blood (e.g., whole blood, withoutsignificant amounts of clot material), and clot material is not nearby,the impedance detected by the bipolar impedance sensor may be theeffective resistance of the blood as current passes through it. Thevolume sensitivity of an impedance measurement will be a function of thesquare of the current density in a given tissue volume, the current arcin a two-electrode sensor may span a larger volume of whole-blood thanit will of clot material. Therefore, as the user guides the suctioncatheter to the clot material (e.g., using fluoroscopy or other guidancetechniques), the impedance measurements may show a measurable increasein effective resistance despite the lack of contact with clot material.Thus, the bioimpedance sensor may establish proximity in addition tocontact with clot material. In blood, at frequencies above 1 kHz, theimpedance sensor may consistently indicate an impedance value below10,000 Ohms, while clot material will return values above 1,000,000Ohms. Note that the actual values of the impedance for blood and/or clotand/or lumen wall may be different depending on the composition of thesensor (e.g., the electrode materials, etc.), however the relativedifferences and the ability to discriminate between these materials(blood, clot material, lumen wall, etc.) may remain. The differencebetween whole blood and clot material impedances may differ on averageby about two orders of magnitude, which is more than sufficient todetermine when full contact with both electrodes has been established.Similarly, the difference between lumen wall and blood and lumen walland clot material may be different, particularly at differentfrequencies within the impedance spectrum.

In any of these methods and apparatuses the apparatus may include asuction catheter that includes a funnel carried by the distal endportion of the suction catheter. Thus, the distal end region of thesuction catheter may be funnel-shaped or may be expanded (having anenlarged diameter) relative to the more proximal portion of the suctioncatheter. The distal face extending across the distal end of the suctioncatheter (including funnel-shaped suction catheters) may be covered byan elastically deformable material, as mentioned above. In someexamples, the distal face comprises a fluid-impermeable material (e.g.,a sheet of elastically deformable material) having a single openingand/or slit(s). With aspiration engaged on the external proximal end ofthe suction catheter, the suction catheter may aspirate clot materialwithin a blood vessel and may remove them (via suction) through thesuction catheter to collect them in an externally housed chamber (e.g.,vacuum chamber). Real-time fluorography may be used to guide the suctioncatheter to the location of the clot material within the vessel(s) inorder to start the aspiration. However, fluorography is not sufficientlyaccurate to control the application of suction, as it may not accuratelyreflect proximity and may not help distinguish between non-clot materialand clot material, as it suffers from information loss due todimensionality reduction. For example, a user may appear to position thedistal face of the suction catheter proximal to a target thrombus,however the distal face may be improperly engaged with the thrombus inthe orthogonal plane. To accurately begin aspiration the user should becertain of proper engagement with the thrombus. In order to establishproper engagement, a measure of proximity must indicate that a majorityarea of the distal face of the funnel is in contact with the thrombus,such that minimal amount of blood is aspirated before the thrombusenters the catheter.

In some examples, the apparatus may include an impedance sensorconfigured to measure impedance to discriminate between the mediaimmediately beyond the distal end of the thrombectomy device. Each celland tissue type in the body exhibits unique impedance and conductivitycharacteristics. When a clot forms in the blood, the normally conductiveplasma becomes entrapped in the fibrin mesh that provides the clotcoherence, and the plasma therefore transitions from conductive liquidto insulated mass. Experimental results show significant increase inimpedance between whole and clotted blood, and this difference inimpedance may be used to distinguish between thrombus and whole blood atthe treatment site. Using an impedance sensor placed at the distal endof the suction catheter and/or within the lumen of the suction cathetermay allow the user to distinguish between engagement with blood andthrombus and to accurately track removal of thrombus material, e.g., byrelying on impedance alone, which removes the need to aspirate bloodbefore recognizing the state of catheter-clot material engagement.

In some examples, the apparatus may include an ultrasound sensorconfigured to obtain ultrasound measurements to differentiate betweenthe blood and clot material at the distal end of the suction catheter.Clot material, blood and vessel wall tissue densities vary measurably,in part due to the varying quantities of cells stored in a unit volumefor each tissue type, which may be governed by the structure of thecells and the means by which they are held together. Blood, as aheterogeneous mixture of cells and liquid, behaves like a lower-densityfluid. Clot material and vessel-wall, however, have higher modulus cellstructures that are more compact, and which allow more cells to exist ina unit space therein. Ultrasound may use cell-density to discriminatebetween the tissue types. Thus, any of these apparatuses may include oneor more ultrasound sensors, e.g., at the distal end of the thrombectomydevice, to discern between clot material, blood, and vessel wall. Insome examples the sensor(s) on the distal end of the catheter includeone or more ultrasound sensors, while the sensors within the lumen arebioimpedance sensors (and in some examples, just bioimpedance sensors).Ultrasound sensors may be used to detect engagement with clot materialprior to activating aspiration.

Alternatively or additionally, one or more optical sensors may be used,e.g., to obtain one or more optical measurements. For example, opticalmeasurements may be obtained from the distal end of the suction catheterto distinguish between clot material, blood, and vessel wall, e.g., byprocessing the light reflection and absorption characteristics (andcomparing to known characteristics of each tissue). Blood, clotmaterial, and vessel wall tissue typically have measurably separateoptical qualities. This may be due to the varying cell structure, cellorganization, and tissue cohesion within each type of material. A lightemitter and light detector, e.g., a photosensor, may be coupled to adetection/emission sensor on the distal end of the suction catheter. Insome examples, the optical components may include a fiber optic materialthat extends to the distal end of the suction catheter for emittingand/or detecting light signals. Such signals may be processed by thecontroller and may use the sensed signals to distinguish betweenthrombus and the surrounding media without engaging aspiration first.Optical sensing may also enable the user to establish proper engagementwith clot material prior to activating suction.

In any of these methods and apparatuses, the apparatus may include acontroller (which may be configured to detect proximity to clotmaterial), a suction catheter, a mounting surface (e.g., on the suctioncatheter), one or more electrodes, an oscillating voltage source, and adata processing unit. The voltage source and/or data processing unit maybe part of or coupled with the controller.

FIGS. 14-16 schematically illustrate examples of apparatuses forcontrolling operation of a suction catheter as described herein, similarto the examples shown in FIGS. 1A and 1C. In all of these examples, theapparatus includes an elongated suction catheter 22, including one ormore sensors 6 for sensing clot on a distal-facing end 31 of the suctioncatheter. The sensors provide data to the controller 7. The controllermay include one or more processors and processing hardware, softwareand/or firmware for processing and analyzing the sensor data receivedfrom the sensors. The controller may also control a suction modulator 13that modulates suction from the suction source 14 (or in some examplesmay directly control the suction source 14). The suction catheter mayconnect to the source of suction and/or a suction modulator via one ormore tubes 15.

For example, in FIG. 14 , the apparatus includes a suction catheter 2having one or more clot sensors 6 disposed externally at the distal end31. Any of these apparatuses may also or alternatively include one ormore clot sensors disposed internally within the lumen of the catheter,e.g., at known distance d from the distal end of the catheter (not shownin FIG. 14 ).

These apparatuses may be used to remove large or small clots, includingclots that are smaller than the length d while inside of the suctioncatheter lumen. When engaging a small clot at the distal end, one ormultiple clot sensors 6 may activate to indicate the presence of clot.Because a small clot may have a diameter less than or equal to thediameter of the catheter 2, not all clot sensors 6 used for establishingproper engagement prior to aspiration may activate despite adequateconditions for aspiring a small clot being met. In such cases thecontroller may determine that aspiration should begin or increase instrength based on a determination from the sensor data that the signalis persistent over time (not artifact) and consistent with clotmaterial. Alternatively, a user may decide to manually initiateaspiration by sending an override command signal to the controller.

Thus any of these apparatuses may include a user interface including oneor more inputs (buttons, touchscreens, knobs, dials, petals, footpetals, etc.) allowing user control and interaction with the apparatus,including the system. The user interface may be part of the controller 7or may be separate from the controller and coupled to it. For example,FIG. 15 illustrates an example including an external unit 33. Thisexternal unit (or external interface unit) may include user controls,such as (but not limited to) a suction start (e.g., valve open) overrideinput, e.g., button, and a suction stop (e.g., valve closed) overrideinput, e.g., button, that may enable the user to manually overridecontrol of the application of signal to either begin aspiration despiteinadequate indicated engagement or stop aspiration despite adequateindicated engagement with clot. Other user inputs may be included aspart of the controller and/or the external unit. For example, userinputs may allow control of the operation of the apparatus, includingthe level of suction, turning on/off the macerator, or the like.

Any of the apparatuses described herein may also include a power controlcircuitry 19 integrated into the control unit 7. The power controlcircuitry may receive power from a wall power line (e.g., plug) and/ormay include a battery. The power control circuitry may power thecontroller, and in some cases the source(s) of pressure, e.g., pumps,and/or the suction modulator, and the drive unit (e.g., motor) fordriving maceration. The power source may be part of the controllerand/or may be controlled by the controller.

The example apparatus shown in FIG. 15 also includes a maceratorassembly including a cutting member 12 and a macerator drive shaft 11and a macerator driver 10. The macerator assembly may also be controlledby (and coupled to) the controller 7. Any of the apparatuses describedherein may include a macerator assembly and may be configured to controlby the controller, using sensor data from sensors 6, including fromsensors 6″, 6′″ within the lumen of the suction catheter 22.

In operation, in some examples a small clot may be proximal to, but notengaged with, the distal end 31 of the catheter 22. The (optional)external clot sensor or sensors 6 may indicate a proximity signal thatis slightly elevated in a manner that is characteristic of anapproaching clot (e.g., the bioimpedance may be elevated above the levelof wall and/or blood when examining the impedance or impedance spectrum,including the change in impedances over time) because of the presence ofclot material. In an engaged state, the distal end of the catheter maybe in contact with clot material such that the clot material (even smallclots) is within, e.g., half of its diameter of the distal end of thesuction catheter and aligned with the opening of the suction catheter.In some instances, a small clot may drift such that it remains proximalto the distal end of the suction catheter in the engaged state yet makessubstantially closer contact with one portion of the distal end and notequal contact with the entire distal end as mentioned above. In someexamples, the system may wait until the clot material is in alignmentwith the distal opening of the catheter before the controller triggersthe application of suction, which may help prevent chipping, slicing, orejection of clot in the treatment area. Alternatively, in some examplesthe controller may be configured to apply an initially higher level ofsuction in order to center and position the clot. During improper orpartial engagement of clot material (e.g., when contacting a smallclot), one or more sensors closest to the location of the small clotrelative to the distal end of the catheter may indicate a measurablyhigher proximity signal to the controller as compared to the proximitysignals of more distal or other peripheral (forward-looking) sensorsremaining sensors that are not in contact or close proximity to theoff-center (“misaligned”) small clot. In some cases, multiple sensorsand/or additional sensing such as x-ray fluoroscopy may supplementproximity sensor signals in order to guide the repositioning of thedistal end of the catheter relative to a clot material.

The example shown in FIG. 16 illustrates an apparatus similar to thatshown in FIG. 15 which also includes a source of positive pressure 18,such as a pump. The controller 7 may directly control the source ofpositive 18 pressure or the controller may indirectly control the sourceof positive pressure by controlling a pressure modulator 13 for thepositive pressure. In FIG. 16 two different pressure modulators (e.g.,including valves, vents, manifolds, etc.) are shown; in some examplesthe same pressure modulator may be used for controlling both negativeand positive pressure. The negative pressure (e.g., suction) source 14and the positive pressure source 18 may both, individually, include oneor more sensors (e.g., pressure sensors 26, 26′) for monitoring pressurefrom the apparatus or within the apparatus. This controller may receivedata from these sensors and may adjust the pressures (including turningon/off adjusting up/down) accordingly. In some examples the controllermay adjust the final pressure or rates of change of pressure byadjusting the sources of negative and/or positive pressure directlyand/or by controlling the one or more pressure modulators 13.

For example, when suction is being applied through the suction catheter,the controller may regulate the amount of the suction (and in some casesthe positive pressure). When a suction modulator 13 is used rather thanadjusting the suction source directly, the controller may maintain avalve in an open state, so that the source of suction is in fluidcommunication with the suction catheter. When applying suction throughthe suction catheter (during aspiration), the clot material may belocated inside of the catheter. In some examples, the controller maycontinually monitor the reported vacuum source state and pressure sourcestate in order to verify successful execution of open and closecommands. If the sensed state or states does/do not agree with theinternally registered state of the controller, an error may begenerated, and the apparatus may temporarily stop applying vacuum(and/or trigger an alert) as a safety measure. In some examples, thevacuum and pressure sources (“reservoirs” or pumps) may contain purgevalves which may be controlled by the controller so that during a deviceerror, the controller may automatically (or a user may manually) executea purge command (e.g., the user may trigger a button disposed on theexternal unit) to actuate the purge valves disposed for the vacuumand/or pressure reservoirs.

The suction catheter may include clot proximity sensors disposedexternally at the distal end of the suction catheter and clot detectingsensors within the lumen of the suction catheter, as described above. Inoperation, these apparatuses may detect that the clot is ingested(including fully ingested) when the distal-facing clot sensors no longerdetect clot. If the internal clot sensors within the lumen of thesuction catheter still detect clot material, the clot has not been fullyingested and removed and suction may remain on. The macerator may alsoremain on. Once clot is no longer detected either outside of the suctioncatheter or within the lumen of the suction catheter, the controller mayturn off the suction until additional clot material is detected. In anyof these cases, the apparatus may enable suction to turn on (and in somecases off), but may require manual input (e.g., via an input such as aswitch, toggle, foot pedal, etc.) to turn on (or off) suction. In somecases, the apparatus may allow the user to select an automatic mode tohave the suction turned on (and/or off) automatically as determined bythe controller. For example, the apparatus may include one or moreexternal distal-facing clot sensors and one or more internal clotsensors within the lumen of the suction catheter. The internal sensor(s)may be, for example, at a distance d from the distal opening of thesuction catheter. The external sensor or sensors may send a baselinesignal (indicating no clot material is present) to the controller whilethe internal sensor or sensors will send a high proximity signal(indicating the presence of clot material) to the controller once theclot material is fully ingested and is within distance d from thecatheter opening. In some examples, proximity signals will communicatebetween the lumen of the catheter and the externally disposed sensors,so that both external and internal sensors send high proximity signalsto the controller, and the controller may jointly analyze the signals todetermine the position of the clot material relative to the distalopening of the suction catheter. In some examples, if the controllerdetermines the position of the clot material inside of the catheterlumen to be past a known, predetermined, distance (or absent), and whenno further clot material is detected in engagement with the distalopening of the suction catheter, the controller may send a close or offsignal to the source of negative pressure (e.g., pump) and/or to asuction modulator. The controller may also verify successfuldisengagement of aspiration. When additional clot material comes intoengagement with the distal end of the suction catheter after theaspiration of clot material, the sequence may be repeated again until nofurther clot material comes into engagement with the distal end of thesuction catheter.

The same general operation may be performed for large and small clotmaterials. For example, a suction catheter with one or more external,distal-facing clot sensors at the distal end and one or more clotsensors disposed internally within the lumen (e.g., at distance d fromthe distal end) may also control suction (and maceration) based on bothinternal signals sensing clot material (e.g., bioimpedance, ultrasound,optics, etc., even without sensing pressure or flow within the lumen)and one or more external signals sensing clot in contact with the distalopening. Any of these apparatuses may determine the relative sizes ofthe clots. For example, a large clot may be defined as a clot of lengthgreater than or equal to d while inside of the suction catheter. Sincelarge clots may present with a narrow, elongated shape, some large clotsmay resemble small clots in engagement with the distal end of thecatheter and in interaction with clot proximity sensors. The controllermay detect that the large clot is fully ingested when the external clotproximity sensor or sensors indicate a baseline proximity signal. Inexamples including sensors within the lumen, the controller may continueto operate the suction (or a reduced level of suction, but not off) whenthe internal sensors indicate that the clot is still within the lumen ofthe suction catheter. For example, the external sensor or sensors maysend a baseline signal interpreted by the controller to indicate no clotin close proximity the distal end of the apparatus, while the internalsensor or sensors send a high proximity signal to the controller,indicating the large clot is fully ingested and within distance d fromthe catheter 2 opening. In some examples, both external and internalsensors may indicate high proximity signals to the controller, and thecontroller may (using both sets of signals) determine the position ofthe large clot relative to the distal opening of the catheter 2 duringingestion and transport clot material to a collection vessel.

Although the apparatuses described herein may be operated withoutpressure sensing within the lumen of the catheter, in some examples apressure sensor may be included. For example, one or more pressuresensors may be disposed internally within the suction catheter eitherdistal or proximal to the distal end of the suction catheter. In suchcases, one or more pressure sensor signals may be sent to the controllerto supplement the clot proximity sensor or sensors disposed eitherinternally or externally on the suction catheter. The pressure indicatedat the proximal end of the suction catheter may be approximately equalto the pressure applied by the pressure modulator or source of suction.The pressure detected near the distal end of the suction catheter, e.g.,within a known distance, d, from the distal opening, may exhibit aslightly higher level when no clot is within the catheter, but mayexhibit a higher pressure approximately equal to that of the mediabeyond the distal end of the suction catheter while a clot material iseither passing over or between the distal and proximal pressure sensors.The pressure signals from the ends of the catheter may enable thecontroller to calculate more accurate representations of the position ofthe clot material within the suction catheter, and this position mayinform commands to the pressure modulator or source or suction, e.g., tostay open in the case of inadequate displacement of clot along thesuction catheter.

As mentioned above, in some examples, the controller may implement amethod of delayed signal processing or delayed signal response in orderto prevent feedback interference with an instantaneous or continuouscontrol system. In such examples, the controller may include a knowndelay (represented by t₁) when stopping suction and/or when startingsuction and/or starting maceration and/or stopping maceration. Separatestart delays and stop delays may be used. The controller may alsointroduce intentional delays before changing the speed of the macerator(e.g., turning on the macerator, turning off the macerator, increasingthe macerator speed, decreasing the macerator speed, etc.). Anintentional delay may also be applied by the controller when updating agraphical user interface or external unit with state information. Theaddition of internal delay (e.g., of 0.5 second, 1 second, 2 seconds, 3seconds, etc. or more) may be beneficial. For example, when thecontroller is using pressure-based internal sensors, changes in theenvironment within the lumen may initially invoke pressure signalfeatures such as random noise or anomalous spikes. In such cases,implementing an intentional delay may prevent the controller fromreacting to illusory or anomalous states by only allowing the controllerto perform an action after data artifacts are expected to have subsided.The duration of the intentional delay may be modified by the controller.For example, the controller may modify the delay over time. In suchexamples, the controller may use a continuous analysis of data patternsand data buffering or recording to enable the controller to autonomouslyconfigure the delay duration. The controller may autonomously configurethe delay duration, or any other variable mentioned herein through knownstatistical methods, including but not limited to data signalprocessing, statistical analysis, thresholding, and artificial neuralnetworks. For example, the value t₁ may be adjusted in order to minimizethe delay t₁ while maximizing the reduction in noise and data artifacts.In some examples, the controller may control a rotating macerator driveshaft that is internally disposed at the distal end of the suctioncatheter as well as a drive motor 10 coupled to the drive-shaft via anattachment to drive rotation (actuation) of the macerator. Thecontroller may be responsible for modulating macerator speed bysupplying or withholding current to the motor and/or by applying controlinstructions (e.g., digital commands). In some examples, the controllermay monitor fluctuations in current drawn by the motor 10 in order tomeasure clot attributes including but not limited to volume, mass,density, or length. Based on such measurements, the controller mayincrease or decrease macerator speed and torque in order to optimize themaceration for a specific clot.

Similarly, the controller may modify the rate of the macerator based onthe one or more sensors within the lumen of the suction catheterindicating the presence of clot material. The sensor output may berelated to the integrity of the clot material, including how hard orcompact the clot material is. Thus, the controller may be configured toset the macerator speed and/or toque based on the intensity of thesignals (e.g., bioimpedance, ultrasound, optical, etc.) from the one ormore sensors within the lumen of the suction catheter. In some examples,the controller may define time-dependent states including but notlimited to clot not moving, rapid clot extraction, stagnant sensorinput, and biased or contaminated sensor input which are determined bythe controller continuously analyzing sensor inputs over a knowninterval t2 after any state change and using any selection of knownanalytical methods including but not limited to statistical inference,thresholding, signal enrichment analysis, noise detection, and datasignal processing. For example, the controller may partially or fullybase control input to any component in electronic communication with thecontroller based on said time-dependent states. Modulating the activityof components such as valves, motors and user interfaces may enable thetreatment of clot according to continuously variable system attributesat the distal end of the catheter. In some examples, the controller maybe in bi-directional communication with all of the components with whichthe controller may interface, including but not limited to sensors,valves, motors, and external user interfaces. The controller may monitorsignals produced by the interfacing components and may include signalsacquired by monitoring of the analysis and state-change actionactivations. In some examples, the controller may monitor a component,peripheral device, signal, or other electronic interface (includingthose not mentioned herein) such that the controller may continuallyregister incoming signals from said interfaces and all devicesinterfacing with the controller which may be capable of continuouslyself-reporting state and data signals and may update the controller withmeasurement data or states at a regular, known frequency. By monitoringcomponents including (but not limited) to clot proximity sensors,pressure sensors, valves, external unit controls, and/or additionaluser-interface controls, the controller may include and incorporateadditional information into control inputs for analysis, thresholding,state coordination, state validation, state-change validation, emergencystate-override, and updating external indications of any states ormeasurements mentioned herein. In some examples the vacuum and positivepressure reservoirs (e.g., pumps) may include pressure sensors disposedinternally for continuously measuring and reporting the pressure withineach reservoir. The controller may use pressure signals from the vacuumand pressure reservoirs, for example, for regulating pressure applied(negative and/or positive pressure) to the suction catheter, forchanging valve states, for modulating the amount of time valves stayopen during aspiration, and/or for inferring pressure inside of thedistal portion of the suction catheter lumen. The controller may applysuction (e.g., by opening one or more valves) for a known time, t₂,before automatically stopping suction (e.g., closing any open valves)and reevaluating, using any selection of available signals and states,whether to reapply suction (e.g., to reopen a valve). This intervalmethod may prevent contaminated sensors, dysfunctional sensors, oldcommands, or other errors that may occur during operation to prevent thevalves from operating. In some instances, the controller's potentialfailure to register a change of state in the system including thevascular region surrounding the distal end of the suction catheter, thesuction catheter, and the interior of the distal end of the suctioncatheter of length d may cause adverse, unsanctioned, or excessiveaspiration or damaging of vessel wall, and parts of the apparatus. Thecontroller may determine that requisite system conditions have been metusing methods and electronic periphery in continuous data communicationwith the controller.

FIGS. 17A-17E illustrate operation of an apparatus such as those shownschematically in FIGS. 1A, 1C and 14-16 . For example, the apparatusshown in FIG. 17A is similar to that shown in FIG. 16 and includes asuction catheter 22 having a central lumen with an opening at the distalend of the suction catheter into the lumen. The suction catheter mayinclude a distal cover, as described above. The apparatus also includesa suction (e.g., vacuum or negative pressure) reservoir 14 and apressure modulator (e.g., suction modulator) 13 including one or morevalves disposed between the suction reservoir and the central lumen ofthe suction catheter. The suction catheter central lumen is in fluidconnection with the vacuum reservoir and (in this example) the pressuremodulator through connecting tubes 15. One or more sensors 6 aredisposed on the distal end 1, which may consist of but are not limitedto monopolar impedance sensors, bipolar impedance sensors, pressuresensors, optical sensors, acoustic sensors, or applied-force sensors.The suction reservoir may include a gas or fluid chamber and a pump forregulating pressure within said chamber, and may be in communication(e.g., constant or periodic, bidirectional reciprocal datacommunication) with the controller. The controller may in turn be incommunication (e.g., constant or periodic, bidirectional reciprocal datacommunication) with the suction modulator 13 and the sensors 6 locatedon the distal end. One or more sensors may be disposed internally withinthe lumen, e.g., at the distal end region within the suction catheter.In some examples the internal sensors are separated by a distance, d,from the suction catheter opening. External sensors 6 may be configuredin multiple arrangements including but not limited to forward-facing andsingular, forward-facing and proximally paired, forward-facing andplurally disposed radially about the catheter opening, andforward-facing and plurally disposed radially about the distal openingwherein each radial position consists of a proximal sensor pair aspreviously described. Internal sensors 6 may be configured in multiplearrangements including but not limited to inward-facing and singular,inward-facing and proximally paired, inward-facing and plurally disposedradially about the catheter wall, and inward-facing and plurallydisposed radially about the catheter wall wherein each radial positionconsists of a proximal sensor pair as previously described. Thecontroller may supply power to the various components of the system,including the sensors. An addressable motor macerator motor 10 is infixed attachment through a flexible drive-shaft 11 with a maceratorcutter 12 disposed at the distal end of the lumen. A user interface(e.g., external unit 13) may be coupled to (or part of) the controllerand may include any selection of control interfaces and informationaldisplays such as LED indicators, buttons, switches, and displays. Theapparatus in FIGS. 17A-17E also includes a positive pressure reservoir18 and pressure modifier 13 for the positive pressure valve, both influid communication with the lumen of the suction catheter through theconnecting tubes 15.

In FIG. 17A the apparatus 1600 is show within a blood vessel, such thepulmonary artery. The distal end of the suction catheter lumen isimmediately surrounded by blood 34. The vessel includes a large clot 13.One pair of forward-facing impedance sensors 6 disposed on the distalend of the suction catheter is monitored by the controller 7. In thisexample, the sensor is configured as a bioimpedance sensor that isbipolar and operates by sending electrical current 35 into the blood 14of the vessel. In FIG. 17A, the large clot 36 is beyond the sensingrange of the clot sensors 6, therefore the impedance value returned bythe sensor is approximately that of blood, and the suction and macerator17 remain off (e.g., no negative pressure through the suction catheter).

As the distal end of the catheter approaches closer to the clot 26, asshown in FIG. 17B, the bioimpedance sensor(s) 6 may detect the clotmaterial as it approaches in closer proximity to the distal end of thesuction catheter and enters a region of relatively high emitted current35. The large clot 36 is close to the distal end; but in this example,the clot material is closer to one sensor 6 out of the pair, indicatingthat the clot 36 is relatively misaligned with the suction catheteropening. In some examples, the controller may turn on suction, or maywait until the clot material is more optimally positioned relative tothe distal end of the suction catheter, as may be detected by the signalfrom the sensor. In some examples, the controller may turn on a briefpulse of higher suction to help better position the clot material.

In FIG. 17C, the clot material 36 is proximal to the distal end 1 andapproximately equidistant to both forward-facing sensors 6. The distalopening is approximately aligned with the clot 13. In this example,current 35 from the sensor(s) on the distal end of the suction catheterpasses approximately symmetrically through the large clot in front ofthe distal opening. The controller may then apply suction through thelumen of the suction catheter. Centering the clot as described above maypermit the clot material to be suctioned without requiring excessiveblood take-up into the lumen of the suction catheter.

As shown in FIG. 17D, the clot is being aspirated into the lumen of thecatheter. The clot material is in contact with sensors both internal tothe lumen as well as with the forward-facing sensors 6. In thisconfiguration the clot material may be detected by the bioimpedancesignal from the internal sensors which emit a current 48 or field, inaddition to the current emitted by the distal-facing sensors. Thecontroller may activate the macerator so that the driver 10 engages themacerator drive shaft 11 to drive rotation of the macerator cutter 12.In some examples the macerator cutter may be positioned more distallywithin the lumen of the suction catheter so that it may enhance take-upof the clot material.

In FIG. 17E the clot material has been fully suctioned into the lumen ofthe suction catheter. The clot material may no longer be detected by thesensor(s) on the distal end of the suction catheter, and the signal fromthe first set of internal sensors 6 may decrease or stop as the clot ismoved proximally through the lumen. In some examples additional sensorsor sets of sensors may be included to track progression of the clotmaterial down the lumen. The controller may continue to macerate andapply suction to pass the clot material for collection proximally.

FIGS. 18A-18E illustrate another example of an apparatus similar to thatshown in FIGS. 1A, 1C and 14-16 , again within a pulmonary artery, inwhich a smaller amount of clot material may be sucked into the device.In FIG. 18A, the distal end of the device is within the pulmonary arteryand the distal end is surrounded by blood 34. A small clot material 39is outside of the range of the sensors (shown here as bioimpedancesensors, emitting a current 25 for detecting impedance). In FIG. 18B theclot material is in closer proximity to the distal end of the suctioncatheter. The clot material 39 is proximal to the distal end but isshown closer to one sensor 6 out of the pair of distal-facing sensors,and the resulting bioimpedance signal shows that the clot material ismisaligned with the catheter opening. As before the controller mayinitiate suction or may wait until the clot is closer (and the sensorsindicate better centering) in order to minimize blood loss.

In FIG. 18C, the clot material is proximal to the distal end andapproximately equidistant to both forward-facing sensors 6 so that thedistal opening is approximately aligned with the clot material. Current25 from the sensor(s) passes approximately symmetrically through thesmall clot 39 in front of the distal opening. The controller may engageaspiration of the clot material into the lumen, as shown in FIG. 18D. InFIG. 18D, the clot 21 is within the lumen entirely, and within the ranged of the first set of internal sensors as described above. In thisinstance of FIG. 18D, the clot material is in contact with sensorsinternal to the lumen 6 (for detection by the emitted current 48) alongwith forward-facing sensors 6. The controller may therefore continueengaging aspiration as the clot material continues into the lumen.

FIG. 18E shows the clot material is fully within the lumen, and whilestill in range of the internal sensors, has passed out of range of theexternal, distal-facing sensors.

FIG. 19 shows one example of a control-loop model for an apparatus suchas the one(s) shown in FIGS. 1C, 15, 16, 17A-17E and 18A-18E. In FIG. 19, the controller may follow the control loop based on input from theclot-sensing sensors within the lumen of the suction catheter and fromthe clot-sensing sensors that are external to the distal end of thesuction catheter 1901. The sensor data may be analyzed to identify whenthe external sensors identify only blood or vessel wall (“externalbaseline”), when clot material is nearby (“proximal”) or when clotmaterial is present on the catheter (“engaged”). Similarly, the internalsensor(s) may be analyzed to determine when clot material is present(“engaged”), nearby (“proximal”) or is absent, and only blood is present(“baseline”). In this simple example of a state diagram, the results ofthe combined external sensor(s) and internal sensor(s) data may set thestate of the suction (on/off) or macerator (on/off). For example, if theexternal sensor(s) indicate that clot material is on the end of thecatheter fully (“external engaged”) and the internal is fully engagedwith clot material (“internal engaged”) 1903, then the suction may be“on,” e.g., by opening a valve in the suction modulator and/or bydirectly activating the source of suction 1905. If the externalsensor(s) indicate that the clot material is absent (“externalbaseline”) or is nearby but not yet in contact (“external proximal”),while clot material is present on the internal sensor(s) (“internalengaged”) 1907, then suction may be applied to continue to remove clotmaterial from within the catheter while the macerator is driven (1909).If the external sensor(s) indicate that the clot material is present(“external engaged”) while the internal sensor(s) indicate either thatclot material is nearby or is absent (“internal proximal/baseline”)1911, then the controller may cause suction to be applied while themacerator is driven 1913. If the external sensor(s) indicate that clotis absent (“external baseline”) while the internal sensor(s) indicatethat clot is absent (“internal baseline”) 1915, then the controller maykeep the suction off (or in some examples, at a low level), while themacerator drive is also off 1917. If the external sensor(s) indicatethat clot is nearby but not in contact (“external proximal”) while theinternal sensor indicate that clot is absent (“internal baseline”) 1919,the controller may set or keep the suction off (or at a low level) whilethe macerator is kept off 1921. Finally, if the external sensor(s)indicate that clot is absent (“external baseline”) while the internalsensors indicate that clot is nearby (“internal proximal”) 1923, thecontroller may slow or stop the suction while continuing to drive themacerator 1925.

In some examples the states shown in FIG. 19 may be interconnected, astransitions between states (not shown in FIG. 19 ) may be predetermined,and the controller may base control states for the suction and/ormacerator based on the prior state. Thus, the state diagram shown inFIG. 19 is exemplary only, and other state diagrams may be used andimplemented by the controller. In some examples, the controller may alsouse data (e.g., feedback) from other components that may inform thestate diagrams and control loop(s). For example, data from the sensorson the negative or positive pressure sources may be used, pressuresensors from within the catheter lumen may be used, user input,including user emergency override input may be used, etc. The primarycontrol layer (“layer 1”) may involve any preliminary data collection oranalysis from peripheral components and exclusively involves functionsof the controller. The secondary control layer (“layer 2”) may involvethe establishment of known system states including but not limited toclot out of range, clot proximal to distal end, clot engaged with distalend, clot within interval d, clot leaving interval d, clotaspirated/return to state clot out of range, etc. Control layer 3(“layer 3”) may exclusively involve control-loop actions such as layerchanges or repeated steps, which in the case of the apparatus shownabove may include returning to the primary control layer. The modelcontrol-loop described herein functions interchangeably with small andlarge clot examples.

Any appropriate macerator may be used. For example, FIGS. 20-24illustrate examples of macerators that may be used. In general, themacerators shown (which may be referred to as shavers”) include an outerhousing 201, shown in FIGS. 20-24 as an insulated or insulating cannula.The outer housing may be flexible, so that the macerator may navigatewithin a curved suction catheter. The macerators shown in FIGS. 20-24may also include an inner housing 202, e.g., in FIG. 20 the innerhousing is an insulated rotating sleeve. The rotating sleeve includes anopening 203 and teeth forming the macerator cutter 204. In some examplesthe macerator may include a single housing in which a flexible maceratordrive shaft (e.g., wire) may rotate to drive rotation of the maceratorcutter. In some examples only a single (e.g., outer) housing is used,and may include a window (or multiple windows) exposing the rotatingcutter. Alternatively in some examples the cutter extends from thedistal end of the housing without sitting within a window.

Any of the macerators described herein may include one or more sensorsfor detecting clot material. In any of these examples the sensor(s) mayform the internal sensors or some (or part) of the internal sensorsdescribed above. These sensors may be clot-detecting sensors, and mayinclude bioimpedance sensors, ultrasound sensors, optical sensors, etc.For example, in some examples the sensors may be configured as bipolarbioimpedance sensors. In FIG. 20 , the macerator includes a monopolarimpedance sensor 205 disposed radially external on the outer housing andproximal to the opening 203 (window exposing the cutter) of the innerrotating sleeve 202. In this configuration the impedance sensor may emitan electrical current 206, shown in FIG. 20 by the dashed linesrepresenting the sensing field of the sensor. Current transferred fromthe monopolar impedance sensor 205 may returns to the sensor 205 afterbeing affected by the surrounding region. Thus, this sensorconfiguration carries lower spatial specificity, enabling clot sensingacross the volume within the distal end of the suction catheter (notshown in this example).

FIG. 21 shows another example of a macerator. In FIG. 21 , a secondmonopolar impedance sensor 205 is disposed on an opposing side of theopening 203 and radially external to the outer housing 201. In thisexample current 206 transferred from each monopolar impedance sensor 205also returns to each respective sensor 205. The sensor configurationcombines lower spatial specificity with multiple measurement locationsradially disposed relative to the opening 203, enabling clot sensingacross the volume within the suction catheter (e.g., the distal end ofthe suction catheter, as well as combined analyses including but notlimited to clot proximity triangulation and signal denoising.

FIG. 22 shows another example of a macerator similar to that shown inFIG. 20 , except with a bipolar impedance sensor 205 replacing themonopolar sensor. In this example, the current 206 transferred from oneelectrode in the bipolar impedance sensor 205 returns through theopposing sensor in the pair 205′. This sensor configuration carrieshigher spatial specificity, enabling more precise analysis of clot nearthe window opening 203. Multiple sensors (including multiple bipolarsensors) may be used.

FIG. 23 illustrates another example of a macerator in which the sensorincludes a pair of electrodes 205, 205′ forming a bipolar bioimpedancesensor that senses the region extending over the opening 202 exposingthe window 203. In this example, current 206 transferred from oneelectrode in each bipolar impedance sensor returns through the opposingsensor in the respective pair. The sensor configuration combines higherspatial specificity with multiple measurement locations radiallydisposed relative to the opening 203, enabling clot sensing andpositioning relative to the opening 203.

FIG. 24 illustrates an example of a macerator inserted through thesuction lumen to the distal end of the suction catheter. As illustratedin FIG. 24 , the distal end of the suction catheter may include anexpanding distal end region into which the macerator may be positioned.A cover 208, which may be elastically deformable and may include anopening or slit to allow passage of clot material, as described above,may be included. In FIG. 24 the macerator includes electrodes 207 thatform sensing pairs of bipolar bioimpedance sensors with electrodes 207′located within the distal end region of the lumen. Thus, sensor pairs207, 207′ are made between electrodes disposed radially proximal to theopening 202 in the outer housing of the macerator and electrode residingon the wall of the suction catheter 209 (in this example, in theexpandable, “funnel” region). The sensor in this example may allowbipolar impedance sensing with high spatial specificity and long-rangecurrent paths 206 in order to provide sensing for the entire volume ofthe lumen of the distal end region of the suction catheter.

FIG. 25 illustrates an example of a distal end region of a funnel asdescribed herein, similar to the example shown schematically in FIG. 24. In any of the apparatuses described herein the suction catheter mayinclude an enlarged (larger diameter) distal end region. This distal endregion may be expandable and collapsible from a compressed undeployedconfiguration (which may fit into a delivery catheter 305. Theexpandable distal end region 303 may be referred to as a funnel regionand may be formed of a material that self-expands when released from thedelivery catheter 305. For example, the distal end region may be formedof a knitted or woven material, such as a polymer or metal (e.g.,nitinol) and may be laminated with a blood-impermeable material. In FIG.25 the suction catheter 300 is shown in the expanded (deployed)configuration, with the distal funnel region shown expanded to adiameter 311 that is many times larger than the more proximal region309.

The distal end face of the expandable region may include a cover asdescribed above. The cover may be an elastically deformable materialthat may prevent blood from entering until suction is applied, which maydeform to allow clot material to enter. The cover may include a slit orslits, and/or a hole that may be elastically enlarged as clot materialis drawn into the funnel region. As described above, the outer distalface (the cover 307) may include one or more external sensors forsensing clot. A macerator may be inserted into the proximal end of thesuction catheter and slid axially into the distal expanded (e.g.,funnel) region, as shown in FIG. 24 . One or more internal sensors maybe present within the inside of the funnel region and or the elongatebody 309 of the suction catheter for detecting clot material within thesuction catheter.

FIG. 26 illustrates methods of sensing clot and distinguishing clotmaterial from non-clot (e.g., vessel wall). In general, the methods andapparatuses described herein may electrically, optically, pneumatically,and/or acoustically interrogate the vasculature of a human and thedevices within the surgical field to inform clinicians during theremoval of obstructive material from the vessels (i.e.: Pulmonaryembolism). Current technologies for removing obstructive material suchas pulmonary emboli from the vessels require the clinician to navigateup through heart and into the pulmonary arteries and blindly search forand attempt to remove the obstructive material from the vessels. In someinstances when using the apparatuses described herein to remove theobstructive material from the vessels, the clinicians access thepulmonary vasculature with a tubular catheter and a guidewire andcontinuously aspirate blood from the body at the proximal side of thevessel in hopes to pull the obstructive to the catheter and eventuallythrough the catheter and out of the body. This approach causessubstantial blood loss, extended procedure time, and increased safetyrisks such as hemodynamic collapse and/or vessel dissection. In someinstances, the clinician will pull vacuum on the proximal end of thecatheter, and nothing aspirates back through the catheter. At this time,the clinician doesn't know if they are stuck causing trauma to a vesselwall or if they are attached to a large obstruction and they should waitand allow the suction to pull the obstruction through the catheter. Dueto these limitations, there is a need for improved thrombectomy systemsthat inform the clinician where the obstruction is located within thevessel, what near and/or within distal end of the system, and when toattempt to extract the obstruction. In the present invention, there areembodiments described that address all of these limitations.

The methods and apparatuses described herein may use at least onesensing element near or attached (e.g., within a predetermined distance,e.g., 10 cm or less, 7.5 cm or less, 5 cm or less, 4 cm or less, 3 cm orless, etc.) from the distal end of the system identifying when devicehas encountered something firmer than blood. When a firmer object issensed, the apparatus may determine if the obstruction is a clotmaterial or a vessel wall, or some other obstruction. For example, theapparatus may automatically and momentarily apply a negative pressure onthe aspiration lumen or informs the clinician to do the same. When thepressure is applied, the system may interrogate (e.g., using at oneother sensor within the aspiration lumen or by otherwise detectingmaterial within the extraction chamber of the apparatus) to determine ifthe system is against an obstructive material (e.g., clot material) or avessel wall. If obstructive material is sensed, the system then appliescontinuous negative pressure and initiates the macerating element tochop up the obstructive material and extract the material from the body.If obstructive material is not sensed within the aspiration lumen, theapparatus will not apply additional negative pressure and may inform theclinician that the apparatus did not encounter obstructive material. Insome embodiments, the apparatus may monitor the removal of theobstructive material being chopped up and removed and reduce or stop thenegative pressure being applied to the aspiration lumen to minimizeblood loss.

For example, FIG. 26 illustrates one example of a method of operation athrombectomy apparatus to detect and remove clot material. For example,in FIG. 26 , the general method may include moving a thrombectomyapparatus within a blood vessel (e.g., advance or withdraw over a guidewire and/or a diagnostic catheter) 2601 to position the apparatus withinthe body. The device may be steered with or without additional guidance(e.g., using fluoroscopy). The apparatus may detect an obstructionwithin a distal region (an “extraction zone”, e.g., within 0-5 cm) of anextraction entrance of thrombectomy device, using, e.g., a contactsensor, a pressure sensor, an optical sensor, a bioimpedance sensor,etc. 2603. Once the apparatus determines that an obstruction present, itmay determine if the obstruction is a clot material or a vessel wall(e.g., from optical sensor, applying suction and determine if drawn intoextraction chamber, by expansion of aperture into extraction chamber,etc.) 2605.

If the apparatus (e.g., a controller of the apparatus) determines thatthe obstruction is a clot material, either by directly sensing aproperty (e.g., electrical, optical, tactile, etc.) of the obstruction,or be determining that the obstruction is capable of being drawn intothe extraction chamber and/or cut by the macerator, which is typicallyonly possible when the obstruction material is clot material based onthe configuration of the apparatuses described herein, then theapparatus may trigger a clot detection response, e.g., an alert/alarm, adisplay, etc., either manually or automatically, and may turn on anextractor sub-system to extract; for example, the apparatus may turn onsuction and/or a mechanical extraction element (e.g., stent, capturetool, etc.), and/or in some examples may turn on and/or increasemacerator activity, etc. 2607. Alternatively if the apparatus determinesthat the obstruction is not a clot material, it may signal to the userto indicate this, and may continue moving the thrombectomy apparatus.

In any of these methods, the method may also optimally include stoppingthe extractor sub-system from extracting material when the apparatusdetermines that clot is no longer detected 2609. For example, theapparatus may stop the extractor sub-system (e.g., turn off suctionand/or mechanical extraction elements) when clot is no longer detectedwithin extraction chamber, e.g., when one or more sensor(s) configuredto sense material within the extraction chamber no longer detect clotmaterial and/or when the apparatus detects a change in maceratorresponse (e.g., current/power use, vibration or acoustics, pressurewithin suction lumen and/or extraction chamber region, etc.) 2611.

FIGS. 27A-27B illustrate examples of thrombectomy apparatuses that maybe configured to perform any of these methods. For example, FIG. 27Ashows one example of an apparatus configured as a suction catheterincluding an elongate body 2713 with a suction lumen, and an extractionchamber region 2703 at a distal end of the catheter. The opening 2721into the extraction chamber region may be referred to as the extractionentrance and may include one or more forward-directed obstructionsensors 2708, 2708′ that are configured to detect or sense anobstruction within the distal-facing extraction zone 2704. The apparatusalso includes a macerator 2717 within the extraction chamber region, aswell as an internal sensor 2710 that is configured to detect materialwithin the extraction chamber. The apparatus also includes a maceratordriver 2717, and optionally a suction regulator 2719, and a controller2715. The controller may receive inputs from the apparatus (e.g., fromthe obstruction sensor(s), internal sensors and/or the macerator driver,macerator sensor, and/or suction sensor). The controller may alsoinclude one or more inputs for the user to enter control commands and/ordata.

The controller may also output one or more outputs 2723 that may includeoutputs (alerts) to the user based on the operation of the apparatus.

In FIG. 27A, the apparatus may apply suction through the maceratorand/or around the macerator. In operation the apparatus may control theapplication of suction and/or the operation of the macerator based oninput from the one or more sensors and/or evidence (e.g., by looking atthe macerator drive) of resistance indicating material within theextraction chamber that may be affecting the operation of the macerator.

FIG. 27B shows another example of an apparatus in which the deviceincludes an elongate body with a lumen (e.g., suction lumen) 4513extending along the length. The distal end region may include a taperingextraction chamber region 2703 that may include an extraction entrance2721 that is at least partially covered by a cover 2729 including anaperture 2743 (e.g., slit) formed through it. The cover may bepermanently placed over the distal-facing extraction entrance, and theaperture may be formed to allow clot material to be drawn in. In theexample shown in FIG. 27B, the apparatus includes a guide channel 2731for passing a guidewire and/or a guide 2735. The extraction chamberregion 2711 may be configured to expand and collapse and may include anextraction chamber sensor 2748 that may be within the extraction chamberor external to the reaction chamber but configured to sense within thechamber. The apparatus may also include a macerator 2717 within thesuction chamber. In this example, suction passes through the maceratorand into the suction chamber. The apparatus may also include a maceratordriver 2717 for driving the macerator, and in some examples a suctionregulator for regulating the suction applied through the apparatus. Acontroller 2715 (including on or more inputs 2725 and outputs 2723) mayalso be included and may include one or more processors, communicationcircuits, etc. The controller may also include wireless circuitry,and/or a memory for storing and/or transmitting data about the operationof the apparatus.

FIG. 28 illustrates another example of a method (which may beimplemented by the apparatuses described herein. In this example, themethod may include moving a thrombectomy device within a blood vessel,e.g., optionally, advance or withdraw the device over a guide wireand/or diagnostic catheter, while preparing to detect an obstruction andsubsequently removing the clot material once detected and confirmed bythe apparatus that the obstruction is clot material 2801.

In FIG. 28 , which shows a particular instance of the methods of FIG. 26, the apparatus and method may be configured to optically detect contactwith an obstruction in an extraction zone of thrombectomy device (e.g.,at one or more sites around extraction entrance) 2803, and to determineif the obstruction is a clot material 2805. For example, the method oran apparatus configured to perform the method may include determining ifthe obstruction is clot or wall, e.g., by comparing reflectance spectralvalues taken from one or more optical sensors configure to detectproperties of a material within the extraction chamber 2805. If theobstruction material is not clot material, the user may be alerted assuch and the position of the apparatus may be adjusted (e.g.,withdrawing away from the obstruction and continuing to advance theapparatus). However, if the obstruction material is determined to beclot material, e.g., based on the reflectance spectral values, a clotextraction response may be triggered 2807. For example, an alert/alarm,display, etc. may be triggered indicating clot material, and theapparatus may manually or automatically turn on/increase suction,manually or automatically turn on/increase macerator, etc. The method orapparatus configured to perform the method may also stop the suction2809 when clot material is no longer detected, e.g., by stopping suctionwhen clot material is no longer detected within extraction chamber(e.g., sensor(s) in suction chamber, resistance in macerator rotation,pressure within suction lumen and/or extraction chamber, etc.) 2811.Suction and/or the macerator may be stropped immediately (or may bereduced) and/or may optionally be stopped or reduced after apredetermined delay, e.g., to allow clot material within the apparatusto clear the elongate suction channel.

FIGS. 29A-29B illustrate one example of an apparatus that is configuredto detect clot material within an extraction region ahead of (distal to)the apparatuses extraction entrance 2921. In this example the apparatusis shown as a catheter apparatus having an elongate body 2913 and adistal end region. An optical sensor 2908 may be positioned distallyforward-looking at or near the distal end of the catheter. In someexamples the optical sensor may be formed of two (or more) opticalfibers; an emitting fiber 2947 and a receiving fiber 2913. As shown inFIG. 29B the apparatus may include a sensing fiber 2913 that is coupledto an optical detector 2938 and an emitting fiber 2947 that is coupledto a light source or sources 2948. The catheter may also include a portfor coupling with a hemostasis port 2942, aspiration port 2940, and/orvalve 2944. As mentioned above, the apparatus may also include acontroller (not shown), a suction regulator (not shown), and optionallya macerator and/or macerator driver (not shown). FIG. 29A shows atransverse section though the distal end region (line A-A′) of theapparatus of FIG. 29A, including the emitting fiber 2947 and sensingfiber 2913, shown positioned on an inner surface of the lumen, but maybe within the wall of the catheter and/or on an outer surface.

FIGS. 20A-30C illustrate the operation of one example of an apparatus asdescribed above. In FIG. 20A the apparatus is guided through the vessel3022 over a guidewire 3022 so that a distal end of the apparatus mayinclude an optical emitter (or emitter/detector) that emits a light 3015of one or more wavelengths, which may be used to distinguish betweenclot material and wall material as described above. In FIG. 30B theapparatus has driven just proximal to the obstruction 3020. In thisexample, the emitting/detecting light may detect the obstruction (orcontact with the obstruction) and suction may be applied 3030, as shown.The suction may remove the clot material. Thereafter, as shown in FIG.30C, the apparatus may be advanced distally over the guidewire, but mayagain hit an obstruction, as shown in FIG. 30C. In this case one or moreindicators may indicate that the obstruction is not clot material, butmay instead by vessel wall, as shown.

FIGS. 31A-31B illustrate examples of two thrombectomy apparatuses thatinclude an elongate body having an extraction chamber region 3111. Amacerator 3117 and/or macerator subsystem (e.g., macerator driver,suction regulator, etc.) may also be included. Suction may be appliedthrough the macerator via a suction lumen 3171. The distal end face ofthe extraction entrance 3157 may be completely or partially covered by acover (e.g., membrane 3159) that includes an aperture therethrough. Thedistal end face may be tapered slightly. In FIG. 31A the apparatus mayinclude an optical sensor 3159 for sensing clot material and/or fordistinguishing clot material as described above. The optical sensor mayinclude an emitting fiber 3161 and a sensing fiber 3163 that are coupledto an optical detector 3146 and a light source 3148. A controller (notshown) may be used to coordinate sensing/detection and the response ofthe apparatus. FIG. 31A illustrates diffused reflectance spectroscopyoptimally positioned to monitor the extraction zone of the system whileminimizing the impact to the aspiration orifice cross sectional area ofthe system.

FIG. 31B shows a similar apparatus in which the optical sensor 3169 isconfigured as a contact sensor also including an emitting fiber 3161 andsensing fiber 3163. The contact sensor in this example may project intothe extraction zone. 3104. FIG. 31B illustrates a distal regionconsisting of a flexible contact sensing element protruding withinextraction zone distal to the aspiration orifice and an interrogatingsensor positioned to optically analyze the object that enters theextraction zone. The flexible contact sensing element in this embodimentcomprises of two flexible polymers fibers made of PMMA adjacentlyaffixed together. The fiber assembly is then jacketed with a protectivepolymer jacket. In other embodiments, it can be conceived by one skilledin the art being reduced to a single fiber. The use of two fibers wasutilized to make the proximal end processing simpler and cheaper. Thedistal ends of the fibers are cut and polished as above and a flexibleoptical finger is affixed over the distal ends. The flexible opticalfinger is designed to be 1-5 mm long, have a diameter range of0.010-0.020″, and a have soft atraumatic distal tip. In this embodiment,the flexible optical finger is made of a low durometer 20-40 shore Apolymer such as silicone with a metallic wire helically wrapped aroundthe polymer. The proximal end of the fibers is cut and polished andattached to a light source and a photon sensor. In use, the light sourcesends light through the emitting fiber into the flexible optical finger.The light shines into the flexible finger and reflects a portion of thelight back through the sensing fiber where the photon sensor detects asignal. If the finger is touched, the amount of light reflecting backchanges causing a signal change at the photon sensor. The elongated bodyof the fiber assembly is positioned within the aspiration lumen of thedevice. In some embodiments, the fiber assembly could have a dedicatedlumen that runs throughout the device. The interrogating sensor of thisembodiment is constructed similarly to the sensor element in FIG. 1above. This interrogating element is affixed to the distal taper of themaceration chamber and positioned so the centerline of the optical lensis traversing the extraction zone. The example also contains anintegrated reinforced shaped catheter with a guidewire lumen, anexpanded collapsible Maceration Chamber having a conformable AspirationOrifice, an elastic Distal Taper, and a proximal end that is affixed toa catheter body that fluidly connects the maceration chamber to theaspiration lumen of the catheter body. Inside the Maceration chamber,the macerator housing having a distal opening and at least one sidewallopening is position and affixed to the distal end of the Catheter Bodyshaft so there is still fluid communication between the macerationchamber and the aspiration lumen. Inside of the Macerator Housing, aMacerator Element having at least one sidewall opening axiallypositioned so that the Housing and Element openings overlap. TheMacerator Element is free to rotate within the Macerator Housing and hasa metallic wire affixed at the proximal end.

In use, the clinician sets up the system and inserts the distal end ofthe system into a lumen within the body per standard minimally invasiveprotocols and advances the system through the lumen towards theobstructive material under fluoroscopy guidance. When an object hits theContact Sensing Element, the Element flexes changing the light intensityon the photon sensor. At this time, the system will inform the cliniciansomething is in the extraction zone of the system using either a visuallight, audible sound, or tactile feel on the handle or base stationoutside of the body. At the same, the system will interrogate the objectusing the interrogating sensing element as described above in a previousembodiment. If the object is obstructive material and within theextraction zone, the system will apply a negative pressure to theaspiration lumen pulling the obstructive material into the macerationchamber and activate the macerating element to chop up the material andallow it to pass through the catheter body and out of the body. Theaspirating and macerating will continue until material is removed fromthe extraction zone. This process can be repeated as many times asneeded.

For example, FIG. 31C illustrates one example of an optical sensor orsensor subsystem that may be used. In this example the apparatusincludes an emitting fiber, sensing fiber, and an optical lens at thedistal end, as well as a light source coupled to the emitting fiber anda sensing element coupled to the sensing fiber. FIG. 31D shows anotherexample of an optical sensor configured as a contact fiber similar tothat shown in FIG. 31C, but with an optical finger projection at thedistal end receiving input from the emitting fiber and output from asensing fiber. The distal finger region may include a flexible member.

FIG. 32 illustrates another example of an optical sensor configured todetect an obstruction as described herein. In this example the sensorincludes an emitting fiber 3105 and a sensing fiber 3107 that terminatein the center of a spherical region having a first index of refraction3113. A region having a second index of refraction 3111 may be presenton the outer region of the sphere and the optical sensor may detect thedifference between the first and second index of refraction may bedetected; contact with the obstruction material 3123 may change theshape of the spherical region and therefore the difference between theindexes of refraction. This may allow the detection of contact with amaterial. In some examples the apparatus may also detect the change inrefraction from contact with the obstruction.

FIG. 33 shows an example of an apparatus in which an emitting 3305 andsensing 3307 portion of the sensor are separated over the diameter ofthe elongate member 3325 at the distal opening into the extractionchamber. For example, the elongate member (elongate body) may be asuction catheter, into which suction 3309 may be controllably applied.

The methods and apparatuses described herein may electrically,optically, pneumatically, and/or acoustically sense the contents withina lumen of a human and the devices within the extraction region Asillustrated above, examples of these apparatuses may have at least onesensing element to detect when an obstruction is located withinextraction zone of the aspiration orifice and to interrogate theobstruction to determine if the obstruction shall be extracted orbypassed (i.e.: Clot vs vessel wall). Other examples have at least twosensing elements to detect when an obstruction is located withinextraction zone of the aspiration orifice and to interrogate theobstruction to determine if the obstruction shall be removed or bypassed(i.e.: Clot vs vessel wall).

In some examples, optical sensing may detect and interrogateobstructions within the extraction zone. An elongated flexible catheterbody with an inner lumen (aspiration lumen) may have a distal andproximal end, a handle with an aspiration port and hemostasis valve, andsensing fiber assembly containing an emitting fiber proximally connectedto a light source, a sensing fiber connected to a photon sensor, and anoptical lens attached the distal end of the fiber assembly as shown inFIGS. 29A-31B. The sensing fiber assembly may be affixed to the innerlumen of the catheter body such that the optical lens of the assembly isaligned (e.g., within 5 mm) of the distal end of the aspiration lumenand runs proximally throughout the catheter body out of the handle wherethe connectorized proximal end of the fibers are connected to a lightsource and photon sensor. The optical lens of the sensing fiber assemblymay be positioned relative to the distal orifice of the aspiration lumenbecause obstructive material within this extraction zone can be broughtinto the aspiration lumen when negative pressure is applied to thelumen. The fiber assembly can be free to move independent of thecatheter body and handle either in a dedicated lumen of the catheterbody or within the aspiration lumen of the catheter body. The fibers ofthe fiber assembly may be made of flexible glass or plastic such as PMMAwith a cladding having a diameter range of 50-500 microns, with apreferred diameter of 125 microns per fiber. The fibers are combined andcovered with an outer protective jacket. The distal ends of two fibersare cut and polished ensuring the distal end is perpendicular to thecenterline axis of the fiber. The distal ends are then potted togetherin a urethane or silicone substance creating the optical lens. Theoptical lens has an atraumatic distal geometry. The proximal end of thefibers may be cut and polished as the distal ends were and each fiberend may be potted into an independent connector (i.e.: SMA, ST, or MUconnectors). In some examples, the proximal end of the emitting fibercould be permanently affixed to a single LED and placed inside thehandle with a small electrical circuit and battery. The flexiblecatheter body of this example is a standard reinforced polymeric shaftconstructed similarly to the flexible elongated shaft as disclosed inU.S. application Ser. No. 17/393,618 which is herein incorporated byreference in its entirety. The handle may be made of a rigid tosemi-rigid plastic such as nylon, abs, or polycarbonate that can beinjection molded or machined. The hemostasis valve may be made of anelastic material such as silicone.

As shown in FIGS. 31C-31D and 32 , optical sensing may utilize diffusereflectance spectroscopy using the fiber assembly to detect andinterrogate an obstruction that is within the extraction zone. The lightsource used may emit a light range of 360-2500 nm and the sensing fiberwill connect to at least one spectrometer to analyze the reflectedlight. In other examples, the emitting fiber(s) may be affixed to aspecific wavelength LED such as 500 nm and the sensing fiber permanentlyaffixed to a sensing element, such as silicon diode. 3 or 4-fiberassemblies may be used that utilizes two specific wavelengths such as480-520 and 1530-1565 nm.

In use, a clinician may insert the system into a lumen within the bodyper standard minimally invasive protocols and advances the systemthrough the lumen towards the obstructive material. As obstructivematerial enters the extraction zone or the aspiration orifice gets nearthe lumen wall, the intensity of the light returning changes and thesystem will either graphically display the changes for the clinician orcompare the intensity readings from a lookup, determine what is in theextraction zone, indicate to the clinician what is in the extractionzone, and/or apply a negative pressure to the aspiration lumen.

The examples described above may use light to detect contact; thecontact sensing element could use an electro-mechanical element thatturns mechanical movement into an electrical signal such as apiezoelectric film or energizing a conductive element like a spring andmonitoring the resistivity change due to wire displacement.

Any of the methods and apparatuses described herein may be configured todetect clot material based on contact pressure. For example, FIG. 34illustrates a method of identifying a clot material and distinguishingthe clot material from vessel wall or other materials, using contactsensing. In FIG. 34 , the method may include inserting and/or advancinga thrombectomy apparatus within a blood vessel of a patient (e.g., overa guidewire, over a diagnostic catheter, etc.) 3401, and detectingcontact with an obstruction at an extraction zone of the extractionentrance of the thrombectomy apparatus, based on contact pressure. Thecontact pressure may be detecting by a contact sensor 3403 such as apressure sensor, e.g., using a contact balloon or other inflated memberthat detects a change in pressure on the material within the contactballoon. Other contact sensors may include optically-based contactsensors, such as those described above (see, e.g., FIGS. 31C, 32D and 32). Other contact sensors may be based on impedance sensing, which maydetect contact by a change in electrical impedance.

Once contact is identified, the apparatus (e.g., using a controllerportion of the apparatus) may trigger an alert indicating contact andmay further identify that the contact is with a clot material or withsome other material, including vessel wall 3405. The step ofdistinguishing between clot material and other (e.g., vessel wall)material may be performed in a number of ways. In some examples, asshown in FIG. 34 , the apparatus may turn on or pulse suction, e.g.,aspiration) through the apparatus if suction is not already beingapplied and may detect that clot material is within the extractionchamber, having entered from the extraction zone though the extractionentrance. In some examples, the closed or semi-closed extractionentrance, which may be at least partially covered by a cover (e.g.,membrane) may allow clot material to pass through the aperture but wouldprevent lumen wall or other material from entering, or entering beyond apredetermined depth into the extraction chamber. Thus, the extractionchamber may be monitored to determine if a material, presumed to be clotmaterial, has entered during the application (e.g., pulse) ofsuction/aspiration 3406. In some examples one or more sensors may bepresent within the extraction chamber or oriented to sense within theextraction chamber (even if outside of our downstream from theextraction chamber), which may sense when clot is present but not vesselwall 3408. In some example, clot material within the extraction chambermay be detected optically (by one or more optical sensors within theextraction chamber), and in general the internal sensor(s) may beoriented to sense at a desired internal proximal position, e.g.,sufficiently far from the extraction entrance to distinguish clotmaterial from vessel wall, such as 2 mm or more (e.g., 3 mm or more, 4mm or more, 5 mm or more, 6 mm or more, 7 mm or more, 8 mm or more, 9 mmor more, 1 cm or more, etc.) within the extraction chamber. In someexamples the method and apparatus may be configured to detect clotmaterial within the extraction chamber by detecting a change in theactivity of the macerator. For example, the macerator may be activatedeither continuously or when sensing clot (e.g., when applying suction,including the pulse(s) of suction); the interaction between clotmaterial within the extraction chamber and the macerator may result in achange in the macerator behavior that is detectable when compared to abaseline (e.g., operated without suction or operated before contact isdetected. In some examples the apparatus may detect contact between themacerator and a clot material within the extraction chamber by detectinga change in the driving energy (e.g., current applied), and/or a changein the rate of activation (e.g., rotation, reciprocation, etc.), and/ora change in the vibration, and/or a chance in the sound of the operationof the macerator. The activity of the macerator may be detectedremotely, e.g., at the proximal end of the apparatus, as by monitoringthe applied energy (e.g., current), the resistance to actuating, etc.

If clot material is detected within the extraction chamber the method orapparatus may trigger a clot detection response. If no clot material isdetected the method or apparatus may indicate this as well. For example,if no clot material is detected, the apparatus may determine indicate analert that the occlusion is likely a vessel wall, and/or may turn off(or reduce) suction and allow the device to be repositioned. Similarly,if clot material is determined to be present in the extraction chamber,the method and/or apparatus may trigger the clot detection response,which may include an alert/alarm (e.g., audible, visual, including butnot limited to emitting or modifying a tone, indicator light(s),display, etc.) indicating that clot material is present, and allow formanual or semi-manual operation of the apparatus. Alternatively oradditionally, the clot detection response may include manually orautomatically turning on or increasing suction, and/or turning on orincreasing the macerator, etc. 3407, in order to remove clot material.The clot detection response may be continued until clot material is nolonger detected. For example, the clot detection response (e.g., suctionand/or macerator activity) may be suspend or reduced if the clot is nolonger detected distally outside of the extraction chamber and/or is nolonger detected within the extraction chamber 3411. In any of thesecases, the clot detection response may be immediately stopped or reducedor may be stopped or reduced after a delay. For example the clotdetection response may be stopped or reduced after a delay of a fewseconds, minutes, etc. to allow clot material to clear though the lumen(e.g., suction lumen) of the apparatus.

FIGS. 35A and 35B illustrate an example of a distal portion of anapparatus 3500 (FIG. 35A) and a proximal portion (FIG. 35B) that isconfigured for contact sensing as described above. In this example, theapparatus includes an expandable extraction chamber region 3511 at adistal end region of the apparatus. The extraction entrance 3557 iscovered by a clover (membrane 3559) in which an aperture (orifice) 3566is present to allow passage of clot material. In this example the cover3559 is flexible and the aperture 3566 is configured as a cut or slitthrough the cover that may expand to pass (and hold)larger clots whileclosing to limit or prevent blood loss when clot is not present. Theextraction chamber is formed on a distal end of an elongatecatheter-like body including a suction lumen (aspiration lumen 3571). Amacerator 3517 is positioned within the extraction lumen and themacerator may fit into and through the catheter body region so that themacerator extends distally into the extraction chamber region 3511. Adrive shaft 3588 extends proximally; in this example the macerator maybe rotated by rotating the flexible elongate drive shaft. The distal endof the extraction chamber, including the extraction entrance 3557 may beangled (e.g., wedge-shaped), concave or convex. In FIG. 35 , theapparatus includes a guide channel 3531 for a guide element 3533 (e.g.,guidewire and/or diagnostic catheter 3537, which may include a pre-bent,steering region).

The apparatus shown in FIG. 35A also includes at least one contactsensor 3559. In this example the contact sensor is a balloon elementthat may connect to a pressure sensor to detect contact with the balloonregion; contact may increase the pressure of a fluid or other materialwithin the balloon and/or an elongate member coupled to the balloon (notshown). The actual pressure sensor may be at a proximal end of theapparatus (e.g., near the proximal end, e.g., FIG. 35B).

Any of these apparatuses may include a proximal handle 3571 coupled tothe outer shaft 3558 that encloses the suction lumen 3571 and maceratordrive 3588. In some examples including a pressure sensor as part of theexternal contact sensor 3559, the contact sensor may be positionedwithin the extraction zone 3504 at the distal end of the device, but thepressure sensor coupled to the contact sensor may be part of or incommunication with the controller 3780 at the proximal end of theapparatus.

In general, a controller may include circuitry for controlling operationof the macerator, suction and/or alerting the user. For example, thecontroller may couple to both the external sensor 3559 in examplesincluding them, as well as any sensors for sensing clot material withinthe extraction chamber; in FIG. 35A the apparatus includes a pressurelumen 3560 that may be coupled to a pressure sensor in communicationwith the controller 3780. The controller may also control operation of amacerator driver (e.g., motor 3473, drive shaft 3588, etc.). Thecontroller may also regulate the suction applied through the suctionlumen 3571, e.g., by coupling to a pump 3577, suction/aspiration tank3375 and/or one or more valves (e.g., bleed valves, etc.). As mentionedabove, the controller may also monitor the operation of the maceratordrive to detect a load on the macerator that may indicate a clotmaterial within the extraction chamber region, e.g., by monitoring thecurrent applied to drive the macerator.

FIG. 35C illustrates an alternative version of an apparatus including acontact sensor similar to that shown in FIG. 35A. In this example thecontact sensor 3559′ is configured as an annular balloon that surroundsthe extraction entrance and the aperture 3566 into the extractionchamber 3511. This may allow for detecting contact around any portion ofthe extraction entrance 3557 within the extraction zone 3504. A pressurelumen (not shown) may couple the internal region of the contact sensingballoon(s) 3559′ with a pressure sensor, which may be monitored by thecontroller.

FIG. 36 illustrates another example of a contact sensor. In thisexample, the contact sensor is an optical contact sensor that may beparticularly well suited to detect contact with a vessel wall or othertissue. For example, in FIG. 35 the sensor includes an emitting fiber3605 that is coupled adjacent to a sensing fiber 3607 so that light 3611emitted from the sensing fiber may reflect off of the tissue and bedetected by the sensing fiber. When the sensing and emitting fibers arein contact with a tissue 3613, depending on the wavelength of lightemitted, characteristic changes in the absorption may be detectedindicating tissue, including oxygenated tissue. For example, the sensormay be configured to detect pulse oxygenation. This sensor may bepositioned external to the extraction chamber and may detect contactwith an obstruction. As mentioned above, any appropriate contact sensormay be used.

FIGS. 37A-37D illustrate operation of an apparatus using a contactsensor to detect an obstruction similar to that shown in FIGS. 35A-35C.In FIG. 37A the apparatus 3720 is advanced forward until a contactsensor 3759 in the extraction region distal to the extraction entranceinto the extraction chamber indicates contact with an obstruction 3720.The controller may detect contact by comparing the contact sensor (e.g.,a pressure sensor coupled to a balloon chamber at a distal end region ofthe device, optical sensor, impedance sensor, etc.) to a baseline. Forexample, if the contact sensor is a pressure sensor, the controller maydetermine that the pressure indicates contact with an obstruction (e.g.,pressure increased above a threshold). The controller may then triggeran alert indicating an obstruction and may determine if the obstructionis clot material by, e.g., triggering or requesting that the usertrigger a pulse of suction, as shown in FIG. 37B. If (as in thisexample) the obstruction is clot material, the material may be drawninto the extraction chamber 3711, as shown. The controller may detectmaterial within the extraction chamber, e.g., by one or more sensorsconfigured to detect material within the extraction chamber, and maytrigger a clot extraction response (e.g., suction, macerator, etc.).

FIGS. 37C and 37D illustrate another possibility, in which theobstruction 3720′ is a portion of the vessel wall (e.g., a bifurcation).For example, FIG. 37C may show the same apparatus after removal of theclot material following FIG. 37B. After removing the clot material thecontact pressure may drop, and the sensor sensing the inside of theextraction chamber may no longer register a material (in some examples,chamber pressure may drop) and/or the macerator driving current maydecrease, indicating the clot material has been removed. The suction maybe reduced or discontinued, and the apparatus may continue to beadvanced. In this example, the contact sensor 3759, in FIG. 37D maydetect an obstruction 3720′, and may apply suction (e.g., a pulse orlow-level of suction) but will not detect the obstruction within (orvery far within) the extraction chamber 3711, since the wall materialwill not be soft/pliant enough to be pulled very far into the extractionchamber, if at all. For example, the contact pressure on the contactsensor may increase, but the sensor within the chamber (e.g., chamberpressure) does not change above a threshold and/or the macerator driverdoes not indicate a significant change in the drive energy (e.g.,current), so the controller concludes no obstruction is present, and mayalert the user that a non-clot obstruction (e.g., wall) is present.

FIGS. 38A-38 illustrate another example of a distal end of an apparatusincluding an aspiration lumen 3803 that includes an extraction chamber3811. The apparatus schematically illustrates an example in which thesensor 3859 is positioned to sense pressure from a distal face of theapparatus (e.g., the extraction region). In this example the sensor is apressure channel coupled to a pressure sensing element that may detectcontact by sensing pressure changes in this region. Alternatively, thesensor may detect a change in flow, if a small amount of positive ornegative pressure is applied; either pressure or fluid flow may bemonitored to detect an occlusion. The apparatus also includes a sensor(configured as a pair of electrical sensors 3860, 3860′ between which animpedance may be measured to detect a material within the extractionchamber 3811. The electrodes are positioned at a recessed location (adistance, x, within the extraction chamber), so that suction appliedthrough the extraction chamber may draw more pliant clot material intothe chamber but will not be likely to draw wall material. FIG. 38B showsanother, similar example, in which a pair of distal electrodes 3859,3859′ may detect contact with an occlusion.

FIGS. 39A-39E illustrate operation of another example of an apparatus asdescribed herein. In this example the controller may monitor pressureand/or flow around the through the apparatus and/or impedance/resistancewithin the extraction chamber. For example, in FIG. 39A the flow aroundthe apparatus is relatively high, while pressure is relatively low, andthe electrical impedance/resistance is consistent with a clear channel(e.g., no material occluding the chamber. As the apparatus approaches anocclusion, as shown in FIG. 39B, the flow and/or pressure may increase,while the electrical impedance within the extraction chamber remains thesame. This may trigger the application of suction (or a pulse ofsuction), as shown in FIG. 39C, drawing the occlusion material into theextraction chamber, resulting in a change in the electrical impedance.Vacuum may be kept high until the occlusion is no longer detected eitherdistally and/or within the extraction chamber, resulting in the flowincreasing and pressure dropping, and the electrical impedance returningto an obstructed value. In contrast, when the obstruction is a vesselwall, as shown in FIG. 39E, the flow may decrease and the pressure mayincrease, but the sensed electrical impedance within the extractionchamber may remain essentially the same, indicating that the obstructionis not clot material, but is likely wall.

The methods and apparatuses described herein may also or alternativelyinclude detection using just one or more internal sensors, e.g., sensingthe region within the extraction chamber, without necessarily using asensor sensing externally ahead of the extraction chamber (e.g., withinthe extraction zone). Instead, suction may be applied periodically or ondemand when advancing or positioning the distal end of the apparatus andone or more sensors may detect a material (e.g., clot material) withinthe extraction chamber. In some examples the resistance to suction maybe monitored to infer an occlusion (e.g., a high resistance to suctionmay indicate that the apparatus is in contact with an occlusion).Alternatively the apparatus may only monitor for material (clotmaterial) within the extraction chamber.

For example, FIG. 40 illustrates one method of controlling clot removalusing a suction pulse. The method may include moving a thrombectomyapparatus within a patient's blood vessel, which may include advancingthe apparatus over a guide wire and/or over a diagnostic catheter 4001.Clot material may be detected within the extraction zone of theextraction entrance of the apparatus (e.g., in front of the extractionentrance) 4003 by activating a macerator within extraction chamber (themacerator may be activated before applying suction in order to get abaseline of macerator behavior for later comparison) 4005, and applyinga pulse of suction (which may be triggered manually or automatically,periodically or intermittently, etc. 4007. The pulse may be, e.g.,between 100 ms and 10 second long (e.g., between 200 ms and 9 second,between 200 ms and 8 seconds, etc.) or longer. During the suction pulsethe controller may determine if a clot material is present in theextraction chamber based on a change in macerator response (e.g.,vibration, sound, current/load, etc.) by comparison to the baseline4009. If clot material is confirmed within the extraction chamber 4011,a clot extraction response may be triggered, as described above (e.g.,alert/alarm, display, etc., manually or automatically turn on mechanicalextractor, e.g., suction, turn on/control macerator, etc.) 4013.

The clot extraction response may be turned off, e.g., stoppingextraction (e.g., stopping or reducing suction or other mechanicalextraction) if the clot is no longer present in the extraction chamber,based on macerator response 4015, either immediately or after a delay.

FIG. 41 illustrates one example of an atherectomy apparatus configuredto perform a method as described above, including a method such asdescribed in FIG. 40 . In FIG. 41 the apparatus includes an elongatebody having a distal end with an extraction chamber region 4103. Thedistal face of the elongate body may include an opening (extractionentrance 4121) into the extraction chamber region. Suction 4119 may beapplied from the proximal end of the apparatus under the control of acontroller 4115 that may control operation of a suction subsystem 4119that may include a suction regulator, pump, suction tank and/or valves.The pump or source of suction may be separate and may be coupled to andregulated by the controller. The control may also control and receiveinput from (and provide output to) a macerator subsystem including amacerator driver 4117 that operates a macerator 4107 within theextraction chamber or positionable within the extraction chamber region4111 of the apparatus. In this example apparatus the controller may alsoreceive input 4125 from a user and may provide the output 4123, e.g.,notifications, mentioned above.

In operation the apparatus of FIG. 41 may periodically (e.g., every fewseconds or more frequently (provide a pulse of suction to see if clotmaterial is drawn into the extraction chamber region from the extractionentrance 4121 and extraction zone 4104. Clot material may be confirmedwithin the extraction chamber when base, e.g., on the behavior of themacerator. For example, the macerator may indicate that clot material ispresent by driving the macerator when suction is being applied todetermining if the response to the macerator is different than whensuction is not being applied, as this difference may be characteristicof the breakup of clot material within the extraction chamber region bythe action of the macerator. For example, the macerator may require alarger power, e.g., current, to operate and/or may otherwise behave asif under a load. In some examples the macerator may generate vibrationsand/or sounds indicating a load is being applied when clot material ispresent.

FIG. 42 illustrates another example of a thrombectomy apparatus similarto that described above, that may also be configured to detect clotmaterial within the extraction chamber 4211 of the extraction chamberregion 4203. In this example the extraction chamber is covered by acover including an aperture forming an entrance 4221 into the extractionchamber. The region distal to the entrance is the extraction zone 4202,and the apparatus may include a guide channel 4231 within which a guide4235 (e.g., guidewire, diagnostic catheter, etc.) may be inserted andused to steer the apparatus. A macerator sub-system 4219 may be includedto drive maceration via a macerator 4207 within the extraction chamber.The macerator may be configured so that suction 4219 is drawn throughthe macerator so that clot material within the extraction chamber isdrawn into and through the macerator. The apparatus in FIG. 42 alsoincludes a controller 4215 that may receive input 4225 from a userand/or from the macerator subsystem and/or from a suction subsystem 4219including a suction regulator. The suction subsystem may be coupled to asource of suction (e.g., pump, wall line suction, suction tank, etc.)and may also include one or more valves. The controller may thereforecoordinate the application of suction and activation of the macerator,either automatically or semi-automatically and/or manually. Thecontroller may also include one or more outputs 4223 for outputtingnotifications to a user (e.g., alerts, messages, etc.).

Any appropriate macerator may be used, including reciprocating (e.g.,biting) macerators, or rotating macerators. For example, FIG. 43illustrates one example of a reciprocating macerator that may be usedwith any of the apparatuses described herein. In FIG. 43 , the maceratorincludes a macerator outer housing 4335 that is enclosed around thecircumference but may be open in one or more macerator windows 4327 andin some examples may be open at the distal end; in some examples thedistal end may be closed. The macerator housing may be elongate and maybe flexible. In some examples the macerator housing may be formed of apolymeric material, or a laser cut hypotube that is flexible along itslength. The housing may be configured to apply suction therethrough(e.g., it may enclose a suction lumen 4333). The macerator housing mayenclose a rotting cutter 4329. In FIG. 43 the cutter is a cylindricalcutter that includes one or more widows (cutter windows 4331) oropenings therethrough. The cylindrical cutter may be configured to fitinto the macerator housing and in some examples, to be retained withinthe distal end region. For example the distal end region may include achannel or waisted region that limits or prevents the cutter from movingproximally and/or distally away from the macerator window(s) 4327 thatare formed in the elongate outer housing. The cutter may be coupled at aproximal end to a drive shaft 4317. In FIG. 43 the drive shaft is a wirethat rotates eccentrically within the outer housing to rotate the cutter4343 so that the cutter window rotates relative to the macerator window,shearing any clot material that is drawn, e.g., by suction, into thewindow region when opened.

In any of the cutters described herein the macerator activity may bemonitored by monitoring the inputs to the macerator sub-system,including the power demand/load on the macerator driver, as mentionedabove. In some examples a macerator sensor 4311 may be included todetect a response of the macerator based on vibration (e.g.,accelerometer), sound (microphone), or the like. The sensor may bepositioned near, including in some examples, adjacent, to the cutter.

Any of the methods described herein may include detecting the presenceof clot and/or distinguishing clot material from other material such asvessel wall, based on the state or response of the aperture into theextraction chamber region in variations in which the extraction entranceis covered by a cover having an aperture. The relative opening state ofthe aperture may reflect the presence of absence of clot material. Forexample, FIG. 44 illustrates one example of a method of detecting clotmaterial and/or distinguishing clot material from vessel wall materialbased on the opening state or response of an aperture through a cover ofthe extraction chamber.

In FIG. 44 , the method may include positioning (e.g., moving) thethrombectomy apparatus within a patient blood vessel, e.g., advancingthe apparatus over guide wire and/or diagnostic catheter 4401. Clotmaterial may be detected within an extraction zone of the extractionentrance (also referred to herein as the aspiration entrance) of thethrombectomy apparatus by detecting the opening of an aperture through acover covering the extraction entrance 4403. For example, the apparatusmay include applying a pulse of suction (e.g., triggered manually orautomatically, periodically or intermittently, etc. as described above)4405, and detecting the separation between two or more sides of theaperture through the cover that at least partially covers the extractionentrance before, and/or after, and/or during the pulse of suction. Theseparation between the two or more sides, which may be flaps, doors,etc. may be detected by detecting via any appropriate technique. Forexample, the opening may be detected by an impedance sensor(s), opticalsensor(s), magnetic sensor(s), etc. 4407. The extent of the opening maybe determined by comparing the separation of the sides of the apertureto a threshold value or range (e.g., based on the separation of thesides prior to approaching clot material) 4409. If the separation isgreater than a threshold value 4411, then the controller (which mayreceive input from the one or more sensors detecting apertureopening/position) may determine that clot material is present based onthe extent to which the aperture is opened; this may trigger a clotextraction response (e.g., alert/alarm, display, etc., manually orautomatically turn on mechanical extractor, e.g., suction, turnon/control macerator, etc.) as mentioned above 4413. Optionally, thecontroller may also stop the clot extraction response (e.g., stopping orreducing suction and/or other mechanical extraction, and/or maceration)when the separation of sides of aperture is less than the thresholdvalue or range 4415.

FIG. 45 illustrates an example of an apparatus similar to that describedabove but configured to detect the opening and/or separation of theaperture. In FIG. 45 , the apparatus includes an elongate body enclosinga suction lumen 4513; the suction lumen may house the macerator 4507that may also enclose the suction lumen for applying suction 4519through the macerator in the extraction chamber 4511. The extractionchamber may extend from the distal end region of the apparatus and mayexpandable/collapsible. The extraction chamber region 4503 may include adistal face forming the extraction entrance 4521 which may be angled,curved (concave or convex) or en face (e.g., flat) relative to thedistal end of the apparatus. The apparatus may also include a guidechannel 4531 for coupling to a guide 4535 (e.g., guide wire, diagnosticcatheter, etc.). The extraction entrance may be covered by a coverincluding an aperture 4566 that may open or close to allow passage ofclot when suction is applied. In the example shown in FIG. 45 theaperture includes a pair of sensors 4505, 4505′ on either side of thisexample of an aperture that may detect the opening of the aperture,including how open it is. In FIG. 45 the aperture is a slit, but otherapertures may be used, including two or more (e.g., three, four, etc.)flaps, valves, etc. The apparatus also includes a controller 4545 thatmay control suction via a suction subsystem 4519 (e.g., suctionregulator, pump, etc., as mentioned above). The controller may alsocontrol the macerator 4507 via a macerator subsystem 4517, such as amacerator driver, etc. The controller may receive input 4525 (e.g. userinput) in addition to sensor input, such as the aperture opening sensorinput. The controller may also provide output 4523 (e.g., notifications,alerts, etc.) to a user as described herein.

FIGS. 46A and 46B illustrate the operation of a pair of aperture sensorson a cover 4612 of an apparatus such as the one shown in FIG. 45 . InFIG. 46A the aperture includes two sides, though apertures having morethan two sides may be used, and a pair of sensors (e.g., a firstaperture sensor 4605, and a second aperture sensor 4605′) are positionedon either side of the aperture 4666. In FIG. 46A the aperture is mostlyclosed; this configuration may represent the baseline of the aperturewhen suction is being applied but no clot material (or other occlusion)is present. Some suction may be applied through the aperture resultingin minimal blood loss. However, when clot is present, the side of theaperture may be separated even more, as shown in FIG. 46B. Theseparation 4615 may represent the side when clot is passed and mayretain the clot until all of it is suction in through the aperture,allowing it to close back to the baseline separation (FIG. 46A). Asmentioned, the sensor may be optical sensors, electrical sensors (e.g.,impedance sensor), contact sensor, magnetic sensors, etc.

FIG. 47 illustrates another example of an apparatus that is configuredto detect and control the capture clot material. In FIG. 47 theapparatus includes an elongate body 4713 that encloses a suction lumen.The apparatus also includes a guide channel (shown with a guide lumen4735). In this example, an external/outside sensor 4708 is also includedfor detecting an obstruction material within the extraction zone 4707 infront of the extraction entrance 4721 into the extraction chamber 4703.Alternatively or additionally, the apparatus may include an impedancesensor (e.g., a pair of electrodes 4758, 4758′) configured as anaspiration opening sensor). The aspiration opening sensor may be on therim of the aspiration opening 4721, or it may be recessed slightly intosuction lumen. In some examples the aspiration opening sensor(electrodes) may be recessed within the rim of the aspiration opening4721; alternatively in some examples, the aspiration opening sensor(e.g., electrodes) are flush with the rim or extend proud of the rim.

One or more internal sensors (forming a sensing subsystem 4710) fordetecting clot material within the extraction chamber may be include. Acontroller 4715 may be used to coordinate the operation of the suctionsubsystem (e.g., suction regulator) 4719, as described above. Theexample shown in FIG. 47 may be modified to embody any of the featuresand/or examples described above. For example, the extraction entrance4721 may be covered by a cover that may include an aperture. One or moresensors may detect the opening state of the apparatus. In some examplesthe external sensor 4735 may be absent. The example shown in FIG. 47does not include a macerator; in some examples the apparatus may beconfigured to include a macerator. The controller may receive input fromthe sensor(s), including the aspiration opening sensor and/or one ormore internal sensors (e.g., impedance sensing electrodes, mechanicalsensors, etc.).

Deflection Sensors

As mentioned above, in any of the methods and apparatuses describedherein, one or more deflection sensors may be used. The deflectionsensor may include a deflectable member that is coupled to a wall of thelumen, e.g., suction lumen, of the apparatus at one end; the second endof the deflectable member is configured to move (deflect) away from aninitial position in a first (undeflected) configuration into a second(deflected) configuration. The deflectable member may be configured tobe elastically deformable, so that it may transition between theundeflected configuration in an unloaded state to a deflectedconfiguration when force is applied by a clot material pushing on thedeflectable member and may return to the undeflected configuration whenthe load is removed from the deflectable member. In general, thedeflectable member is configured to project into the lumen of thesuction lumen.

The deflection sensor (and the apparatus including the deflectionsensor) may also include a sensing circuit to detect deflection of thedeflectable member and encode deflection as a signal that may be used bythe controller to detect a clot material and/or to distinguish between aclot material and a wall of the lumen. In particular the controller maybe configured to use the signal from the deflection sensor and/or fromone or more other sensors (e.g., pressure, flow, etc.) to determine thatclot material is trapped in the suction lumen.

For example, FIGS. 48A-48C illustrate one example of an apparatusincluding a deflectable member 4855 configured to detect clot materialwithin the distal end region (e.g., an extraction chamber region 4803)of the elongate body of the aspiration catheter 4800. The aspirationcatheter includes an elongate body and a suction lumen 4813 extendingfrom a distal end to a proximal end. In the example shown in FIG. 48 theaspiration catheter includes an extraction entrance 4821 at the distalend that is angled relative to the long axis of the catheter. Theaspiration catheter also includes a guide channel 4831 within which aguide 4835 may be used to help navigate and position the apparatus. Theguide 4835 may also be used to pass a guidewire. In this example theextraction entrance comprises a cover partially covering the distal end(forming a lip region).

In FIGS. 48A-48C the deflectable member 4855 is configured as a whiskerthat is configured to assume a first, undeflected, configuration (shownas a solid line) at rest, extending proud of the wall of the lumen, andtraversing the suction lumen. In the example of the deflectable membershown in FIGS. 48A-48C, the deflection sensor including the deflectablemember is configured to electrically detect displacement of thedeflectable member. For example, a sensing circuit may include a firstelectrode 4856 that is positioned on the opposite side of the lumen fromthe base of the deflectable member. A second electrode 4857 ispositioned on a distal end of the deflectable member 4855 and may beseparated from the first electrode 4856 by a small distance in theundeflected configuration (or in some examples, may touch the firstelectrode). Optionally, a third electrode (not shown) may be included atan axially (e.g., longitudinally) offset position but on the same sideof the lumen as the base of the deflectable member. As will be describedin more detail below in FIGS. 51A and 51B, the deflectable member andelectrodes may be used to detect deflection of the deflectable member inuse.

For example, FIG. 48B shows the apparatus of FIG. 48A following theapplication of suction, including a pulse of suction. In this example aclot material 4820 is shown trapped (jammed) within the distal endregion (e.g., the extraction chamber region 4803) of the apparatus. Thedeflectable member is shown fully deflected so that the second electrodeon the distal end of the deflectable member 4855 is pushed away from thefirst electrode 4856. In this example the deflectable member 4855(whisker) is thin and extends across virtually the entire diameter ofthe lumen. In some example, the deflectable member extends onlypartially across the diameter of the lumen. The deflection sensor mayprovide a signal indicating that the deflectable member is deflected fora prolonged period of time, indicating that the clot is trapped in thedistal end region of the apparatus. In some examples the controller maydetermine that the clot is trapped and may alert the user to deploymanually (or may automatically deploy) a macerator 4807 to help removethe clot material. In some examples the macerator may beinsertable/removable, as shown in FIGS. 48A-48C, or it may be held inposition at the distal end region (e.g., within the extraction chamberregion, which may also be referred to herein as a macerator chamber).For example, in FIG. 48C the macerator 4807 may be driven distallythrough the aspiration catheter suction lumen until it reaches a stop4857 that prevents it from cutting the deflectable member 4855.Maceration of the clot may be performed with continuous and/or pulsatilesuction.

In general, the deflectable member 4855 may be positioned within thesuction lumen near the distal end at a position that prevents it frombeing substantially deflected by vessel wall that may be drawn partiallyinto the lumen of the aspiration catheter but may allow it to berobustly deflected by even more rigid clot materials. For example, insome examples the deflectable member 4855 is positioned within thedistal x mm of the distal end opening (e.g., distal 20 mm, 18 mm, 15 mm,14 mm, 12 mm, 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, 1mm, etc., e.g., between 1 mm and 25 mm, between 2 mm and 25 mm, between3 mm and 25 mm, between 4 mm and 25 mm, between 5 mm and 25 mm, between2 mm and 20 mm, between 3 mm and 20 mm, between 4 mm and 25 mm, between4 mm and 20 mm, between 3 mm and 15 mm, etc.). In examples (such asshown in FIGS. 48A-48C) in which the distal end opening is angledrelative to the long axis of the catheter, the deflectable member 4855may be positioned within 5 mm from the most proximally-positioned end ofthe opening. For example, the deflectable member 4855 may be between 2mm and 20 mm of the distal end opening.

The example shown in FIGS. 48A-48C illustrate the use of electricalsensing to monitor the deflection of a deflectable member within theaspiration orifice (e.g., aspiration lumen) of an aspiration catheter toremove clot more efficiently from a blood vessel. The apparatus in thisexample includes an elongated shaft having a distal end and a proximalend defining a lumen, at least two electrodes 4857, 4856, and a proximalhandle (not shown). The first pair of electrodes may be positionedaxially within about 5 mm of the distal end and radially within the sameplane (e.g. transverse to the long axis of the catheter). The secondelectrode is exposed at the distal end of the deflectable member 4855includes a distal and proximal conductive section and an insulated bodythat runs the length of the elongated shaft of the deflectable member,within the wall. The distal section of the electrode then extends fromthe surface of the elongated shaft through the longitudinal axis of theinner lumen and is positioned within about 0.01-2 mm from the firstelectrode which is on the inner surface of the inner suction lumen 4813.A small area of the distal section of the second electrode near thefirst electrode may be conductive with the remaining portion of theelectrode passing through the lumen and is insulated.

As mentioned, the deflectable member that extends across the aspirationlumen may be configured to be flexible and in some examples may have aminimal surface area to minimize the area being obstructed within thelumen it is crossing. The flexibility of the deflectable member allowsthe second electrode to easily flex outwardly towards the inner surfaceof the lumen away from the first electrode on the opposite wall when asufficient force is applied; the deflectable member may return tostarting position when the force is removed or lessened. The firstelectrode may be built into the inner surface of the suction lumen and aconductive area of the first electrode may be positioned to encounterthe fluid or objects that pass through the aspiration lumen. Thus, thefirst electrode 4856 may be flush with the wall of the suction lumen,recessed into the wall of the suction lumen or may extend slightly proudof the wall of the suction lumen. When the electrodes are energized andplaced in a conductive solution such as blood, as the electrodesseparate, the resistance between the electrodes increases. The change inresistance and the duration of this change can indicate if there issomething within the lumen, just attached to the distal end of thelumen, and/or passing through the lumen.

In some examples the elongated shaft of the deflectable member isconstructed of a polymeric inner liner (e.g. Pebax, PTFE), a reinforcedlayer (e.g. SS braided wire), and a polymeric outer jacket (e.g. Pebax).The electrode at the end of the deflectable member may comprise of a0.0005 to 0.003″ round polyurethane coated copper wire (Magnet wire) anda 0.003-0.015″ nitinol wire. The wires may be laid side by side togetherand joined together so that at least the distal ends aligned. In oneexample the wires are head together by dipping at least 5 mm of thedistal section into silicone and allowing the silicone to dry. In doingthis, the two wires may have a thin coating, e.g., less than 0.003″thick, surrounding the wires. The distal end of the magnet wire may thenbe exposed by removing the polyurethane and silicone coatings creating asmall conductive section. In some embodiments, the exposed conductivesection could be just proximal, ˜0.5 mm, from the distal end of thedeflectable member. The first (e.g., luminal wall) electrode maycomprise a thin polyurethane coated copper wire (magnet wire) that isconductively affixed to a thin sheet (0.001-0.010″ thick) of conductivematerial (e.g. copper). The body of the electrodes may be integratedinto the elongated shaft by laying the insulated electrodes along theouter surface of the inner liner or reinforced layer. The outer jacketmay then slid over the electrodes and elongated reinforced layer andshrunk down using heat and heat shrink to trap the electrodes in placealong the body of the shaft. The thin conductive film of the secondelectrode is folded around the distal end of the inner liner andcompressed into the inner liner affixing it in place. The distal sectionof the first electrode may then pierced through the inner liner near thesecond electrode and positioned through the longitudinal axis of theaspiration lumen so that the conductive section of the first electrodeis within about 2 mm from the conductive section of the secondelectrode. The proximal ends of the electrodes may then extend to adistal end of the catheter (e.g., to the handle) to allow the circuit tobe completed and energized/monitored, e.g., by a controller.

FIG. 49 shows a first example of an apparatus including an aspirationcatheter 4900, a macerator 4907 that may be inserted/removed from theaspiration catheter and a controller 4915 controlling the application ofsuction through the macerator and/or aspiration catheter. The apparatusalso includes a deflection sensor including a deflectable member 4955for detecting when clot material is in the distal end of the aspirationcatheter. In this example the aspiration catheter also includes one ormore additional deflection sensors (including a second or moredeflectable member 4955′) located along the length of the suction lumen4913 of the aspiration catheter. The deflectable members 4855, 4855′ areshown in the un-deflected configuration by solid lines and in adeflected configuration by the dashed lines.

In FIG. 49 , the aspiration catheter 4900 includes a distal end opening4921 into the suction lumen (the distal end region extending proximallyfrom the distal end opening may be referred to herein as an extractionregion of the suction lumen). As mentioned, the deflectable member 4955may be positioned slightly proximally relative to the distal end opening4921 so that it will detect clot drawn into the distal end openingduring suction pulse but will not be significantly deflected by a vesselwall. For example it may be recessed between 2 mm and 25 mm into thesuction lumen 4913. The spacing may be dependent upon the diameter andorientation of the distal end opening 4921. In examples in which thedeflection of the deflectable member 4855 is detected electrically aspart of a detection circuit, the deflectable member may include anelectrode at the deflecting distal end region and an electrode may bepositioned opposite from an electrode 4956 on the lumen wall. In someexamples one or more additional lumen electrode may be include (e.g.,axially offset and on the same side of the lumen as the base of thedeflectable member. The proximal end of the aspiration catheter mayinclude a handle (not shown) and/or may include a hemostatic valve 4962into which the macerator 4907 may be inserted, either manually orautomatically (e.g., robotically) the macerator 4907 may include anelongate body and a distal cutter, such as a rotatable cutter. Themacerator may also include a suction lumen (macerator suction lumen) andmay include a drive member such as a drive wire (not shown) for drivingrotation of the distal cutter.

In general, the controller may control the application of suctionthrough the catheter 4900 and/or macerator, e.g., via a valve, such as a3-way valve 4963. Alternatively or additionally, this valve may bemanually controlled. The valve may allow suction to be applied from thevacuum pump 4919, which may pass through a clot reservoir 4964 to allowviewing of the clot material (e.g., through a transparent window), andfiltering of blood through one or more filters 4965 into a bloodcollection reservoir 4966. The controller may also control the drive4917 driving rotation of the macerator cutter (e.g., via a drive shaft,not shown). The drive may also or alternatively be manually controlled.

The controller may include one or more inputs (e.g., keyboard,touchscreen, buttons, touchscreens, dials, sliders, knobs, etc.) and oneor more outputs (screens, lights/LEDs, speakers, etc.). In any of theseapparatuses the controller may also receive input from the one or moredeflection sensors. The controller may determine, based on thedeflection of the deflectable member(s) 4955, 4955′, if clot material iswithin the lumen of the catheter 4900 and may trigger one or moreoutputs (e.g., a clot extraction response). For example, in some casesthe controller may apply or coordinate the application of a pulse orpulses of suction from the aspiration catheter 4900 and may determine ifclot material is drawn into the suction lumen through the distal end4921. Deflection of the deflectable member at the distal end 4955 in asustained manner may include that a large clot is present at the distalend region the controller may be configured to trigger an alert so thatthe user may apply more sustained suction and/or may insert and use themacerator 4907 to remove the clot material if it is trapped at thedistal end of the aspiration catheter.

FIG. 50 illustrates another example of an apparatus including anaspiration catheter 5000 (shown within a vessel 5001. The catheter 5000includes a catheter shaft 5013. A deflection sensor including adeflectable member 5055 (configured as a whisker W1 in this example) ispositioned at a distal end region within the suction lumen of theaspiration catheter. The aspiration catheter also includes a seconddeflection sensor including a deflectable member (W2) 5055′ at theproximal end of the suction lumen. The catheter also includes ahemostatic valve 5062 through which a macerator shaft 5083 may beinserted manually or automatically. In FIG. 50 a valve (e.g., 3-wayvalve) 5063 is included to switch between applying suction to theaspiration catheter or the macerator (or neither). The valve may be amotorized 3-way valve (MOT) and may couple the catheter and/or maceratorto the vacuum blood reservoir 5066 through a filter 5065 and clotreservoir 5064. The vacuum pump 5019 may be coupled to the catheterand/or macerator through the reservoir 5066. A controller 5015 may beused to coordinate the suction, macerator and/or sensor(s).

In any of the apparatuses described herein the controller may alsocoordinate the application of suction through the aspiration catheter5000 and/or the macerator 5083 based on patient respiration and/orpressure within the blood vessel local to the distal end of theaspiration catheter. For example, suction may be applied in a pulsatilemanner when (or only when) local pressure is low during the cycle of theblood pressure pumping the vessel.

Thus, and of these apparatuses may include a blood pressure transducer5072 (P1). The pressure transducer may be on the catheter at or near thedistal end or it may be separate, including external. Alternatively oradditionally a distal catheter shaft pressure transducer 5071 (P2) mayalso be included on the aspiration catheter. The catheter may alsoinclude a proximal pressure transducer 5073 (P3). Any of theseapparatuses may also include one or more flow sensors/flow transducers5077 (F). In FIG. 50 the flow transducer is near the proximal endsuction port. The controller may receive input from any or all of thesesensors/transducers in addition to the deflection sensor(s).

The macerator may also include a drive in the macerator handle 5081 ormay be in communication with the handle (Mac) and the controller mayalso receive input/direct output to the handle, allowing the drive to beturned on/off and/or increased/decreased.

In FIG. 50 the controller may coordinate one or more pulses of suctionfrom the aspiration catheter based on the sensed pressure way of theblood vessel 5079 and may detect clot material entering and/or exitingthe suction lumen via the two deflection sensors.

FIG. 51A illustrates the operation of a system such as those shown inFIGS. 48 and 49 . In FIG. 51A the deflection sensor detects impedancechanges as a function of the distance between the tip 5157, 5157 x ofthe deflectable member 5155 and an electrode 5156. When the delectablemember (e.g., “whisker”) deflects towards an axial position as the clotpasses over it, the distance between the electrode on the opposite walland the tip of the deflectable member 5157 increases and therebyincreases the impedance between those two points which is reflected inthe impedance measurement Z 5190. The impedance measurement may beperformed at a single or at multiple frequencies. The frequency rangecould be, e.g., between 0 Hz (DC measurement) to 100 kHz, and morespecifically from few Hz to few kHz, for example around few hundred Hz(e.g., 100 Hz-900 Hz, 100 Hz-700 Hz, 100 Hz-500 Hz, 100 Hz-400 Hz,etc.). In any of these examples, the frequency may be further tuned tobe a multiple of 50 Hz and 60 Hz to reduce the amount of power lineinterference specially when a long cable is used to reach the distal endof the catheter. Some examples of such frequencies may include 300 Hz,600 Hz, 900 Hz etc. The higher frequencies may be susceptible to thelong cable length stray capacitance/inductance and may experiencecross-talk, however long cable length may be advantageous for reducingthe effect of electrode/electrolyte interface impedance. Therefore, amid-range frequency, e.g., of a few hundred Hz may be optimal for thistype of measurement.

Compared to the DC measurement, the advantages of the AC measureinclude: the signal may be less sensitive to induced noise because themeasurement could be performed at the same frequency using a lockingamplifier or using synchronous demodulation (which has the advantage oflower cost implementation), the AC may be less susceptible to theelectrode/electrolyte interface specially the double layer capacitancedeveloped at such an interface. The impedance measurement may beimplemented the by two wire or 4 wire techniques described herein.

Alternatively, in some examples, the sensing circuit may instead includea second wall electrode, as shown in FIG. 51B. In this circuit theelectrode 5157 at the distal tip of the deflectable member 5155 movesbetween the first electrode 5156 and the second electrode 5156′. Thesensing circuit therefore allows sensing (V_(out)) of deflection bylooking at the output voltage which varies depending on the tipposition. In this example the deflectable member (e.g., whisker)position acts like an impedance divider, to divide the source AC signalinto a value proportional to the relative position of the whisker to thesource electrodes. This approach may be less sensitive to the absoluteimpedance value of the media (e.g., blood or blood clot) but may be moresensitive to the relative position of the deflectable member. Also thistechnique may be less sensitive to the accuracy of the impedance sourcevoltage magnitude and frequency. This technique may convert the absoluteimpedance measurement to ratio-metric measurement which may be lesssensitive to the measurement variations. Also, the AC signal may besinusoidal, square wave, sawtooth or any other (including arbitrary)shape. The output may be calculated based on the RMS value of thesignal.

FIG. 52 is a graph that illustrates the use of a deflectable member todetermine characteristics of clot sensing in the distal end of theapparatus. For example, in FIG. 52 there are three possible scenarios ofaspiration and shows graphs illustrating schematically how each of thesecases would be reflected in the deflection of a deflectable member atthe distal end region of the aspiration catheter, as well as the flowrate and pressure within the aspiration suction lumen. For example, inFIG. 52 at the far left side, the case in which no clot enters thecatheter during a pules (100 ms pulse) of suction is applied through theaspiration catheter including a deflectable member. Deflection in thisexample may be determined by the impedance change of a sensing circuit(such as that shown in FIG. 51A). A small increase in impedance duringthe pressure pulse is seen but falls off as the suction is turned off.The flow rate increases maximally during the application of suction,whereas the catheter shaft pressure is modestly decreased duringsuction. During the period when the valve is fully open for 100 ms, amaximum flow occurs through the catheter, as shown. In contrast when thepulse of suction causes material to clog as shown by the middle columnin FIG. 52 , a large piece or pieces of clot material may be stuck inthe distal end of the catheter. In this case, the deflectable member(e.g., whisker) deflection signal stays on even after the valve is shutoff. In addition a much lower flow is seen, with a rather large pressuredifference. In contrast if the vessel wall is engaged by the distalopening of the catheter, the deflectable sensor will not detect thedeflection of the deflectable member, as shown, similar to the case inwhich no clot material is detected. In contrast, however, thedeflectable member deflection may have similar flow, and pressureprofiles as when the catheter is not occluded (far left scenario). Forexample, the pressure may increase during suction, but the flow rate mayremain relatively low.

In general, the controller may use data such as that shown above, whichmay be collected using all or a subset of these components (e.g.,sensors).

In some examples the system may initially close suction (e.g., the threeway valve) to prevent any suction through the macerator or aspirationcatheter and may start and run the vacuum pump until the reservoirvacuum pressure reaches a target range (e.g., −700 to −760 mmhg). Atthis point the user can activate the valve by pressing one of thecontrols (e.g., buttons) on the catheter shaft and may aspirate salinethrough the catheter to prime the system before insertion into thepatient's blood vessel. Once the system is done with the initial set up(and any self-check steps), it is ready for operation.

The user may then insert the aspiration catheter into the patient'sblood vessel and advance it until it reaches the target area, in orderto perform a thrombectomy procedure using these apparatuses. At thispoint, the catheter tip may or may not be close enough to the clot tocapture it by aspiration. In order to limit the blood loss, the systemmay activate the vacuum for a very short interval, for example 20-100 msand then assess the sensors to see what the combination of informationfrom the pressure sensors and/or the deflectable members indicate. Asshown in FIG. 52 , the first scenario is that of the tip of the cathetermay be too far away from the clot and therefore unable to capture itwhen vacuum is activated. In this scenario, the valve is opened to its100% of opening window and for a period of 100 ms. The catheter pressuremeasure by P2 goes negative but not to the maximum vacuum pressure giventhere is free flowing blood through the system. The deflectable member(e.g., whisker W1) moves a small amount due to the flowing bloodexerting force on it but not to its maximum.

In the second scenario a large clot gets stuck at the tip of thecatheter upon opening of the valve. The clot does not allow any flowother than some leakage around it, thus the pressure goes to nearmaximum, flow is minimal but the deflectable member (e.g., whisker W1)signal goes to its maximum level given the clot is pressing it to theside of the catheter lumen. Once the valve is closed, the whisker signalstays high as the clot is still present and needs to be macerated orotherwise forced to move.

In the third scenario, the tip of the catheter is placed against thewall of the vessel and upon opening of the valve, the wall is suckedinto the opening of the catheter and blocks any fluid flow barring somepossible leakage. In this case, pressure goes to near maximum vacuumwhile there is minimal flow signal and no whisker signal barring aminimal amount due to the leakage of blood into the catheter.

FIGS. 54A-54C, 55 and 56 show other examples of deflection sensors thatinclude deflectable members. In any of these deflection sensors thedeflectable member is configured so that a first part of the deflectablemember is fixed to the suction lumen and a deflected end extends atleast partially into the lumen so that force due to a blood clotcontacting it deflects it. In FIGS. 54A-54C the deflection sensorincludes a deflectable member 5455 that is configured as a deflectablespring within the suction lumen. The spring may be relatively easilymoved within the lumen of the suction lumen with the distal end fixedand the proximal end free to move. The sensing circuit may include aninductance sensor (e.g., an inductance-to-digital, LDC sensor) 5447 thatcan be used to detect a change in impedance/inductance, as shown in FIG.54B. As force (e.g., dure to a clot entering the distal end opening 5421and pulling on the spring proximally under the force of suction, or whenjammed into the distal end region) pulls the spring proximally, thechange inductance may be detected, as shown in FIG. 54C.

FIG. 55 shows another example of a deflection sensor including adeflectable member 5555 in an aspiration catheter 5500 that includes ashape sensing optical fiber (e.g., an optical fiber bend sensor) near adistal end opening 5521 into the suction lumen. Bending of thedeflectable member results in a signal of the optical shape sensor 5549that reflects bending of the deflectable member 5555. In this example.As in any of these examples the deflectable member may be restored tothe undeflected configuration when the force (e.g., the clot) isreleased or removed, e.g., by aspiration and maceration.

FIG. 56 shows another example of an apparatus 5600 including adeflection sensor with a deflectable member 5655 and a sensing circuitproviding a deflection signal to the controller. For example, thedeflecting member may include a material for which resistivity changesas it is bent. Thus, bending of the elongated deflectable member 5655causes an increase in resistance across the conductive elements. Theelongated deflectable member may be similar to sensors of the typeavailable from Flexpoint Sensor Systems, Inc. of Draper, Utah. Thedeformable member 5655 may be secured to the side of the lumen asdescribed above, e.g., by adhesives, fasteners, or other suitabletechniques, within a predetermined distance from the distal end opening5621. Alternatively a current source can be used to drive the resistiveelement to create a higher range signal.

FIG. 57 illustrates another example of an aspiration catheter apparatus5700, similar to that shown in FIG. 56 , including a deflection sensorwith a deflectable member 5755 and a sensing circuit providing adeflection signal to the controller. For example, the deflecting membermay include a material for which resistivity changes as it is bent.Thus, bending of the elongated deflectable member 5755 causes anincrease in resistance across the conductive elements. The deformablemember 5755 may be secured to the side of the lumen as described above,e.g., by adhesives, fasteners, or other suitable techniques, within apredetermined distance from the distal end opening 5721. In thisexample, a current source 5793 can be used to drive the resistiveelement to create a higher range signal. A controller may process theoutput voltage to detect deflection.

FIG. 53 illustrates one method of operating an apparatus including adeflectable sensor as described. Optionally the apparatus may bepositioned within a vessel of a patient 5301 near a clot material. Theapparatus may then detect clot material 5303 near the distal end openinginto the device by applying a pulse of suction 5305 and detectingdeflection of a deflectable member 5507 (e.g., by detecting deflectionof deflectable whisker based on electrical signal between tip of whiskerand reference (fixed) electrode in lumen). The resulting signal(s) maybe analyzed to determine if a clot material is present in the distal endof the device, and/or if the aspiration catheter is against the vesselwall. For example, the deflection signals may be compared from theperiod of time before/during and after the pulse. Optionally thepressure and/or flow may be analyzed. As described in FIG. 52 , the clotmay be distinguished from vessel wall or non-clot scenarios. If theobstruction is detected and is a clot 5311, the apparatus may trigger aclot extraction response 5313, such as alerting the user that the clotis present (in some cases the system may instead indicate the wall ofthe vessel has been contacted), and/or turning on suction and/or turningon maceration. Optionally the method may include stopping extraction(e.g., suction) where the deflection sensor no longer detects deflectionof the deflectable member indicating that clot is present 5315.

FIGS. 58A-58C illustrate examples of impedance-based sensing systems fordetecting clot material within the lumen. In any of the apparatusesdescribed herein, the sensor(s) within the lumen, which may generally bereferred to herein as intraluminal sensors, shown as impedance sensorsin FIG. 58A, include a pair of sensing electrodes 5860, 5860′. Theseintraluminal sensors may be positioned within the lumen of the distalend region of the aspiration catheter 5800 at a specified distance fromthe distal end opening 5821 so that a clot material may jam within thedistal end region in contact with both the first 5860 and second 5860′electrodes, changing the impedance between the two, including changingthe impedance when measured at different frequencies, as describedabove. The spacing distance from the distal end opening may be selectedso that clot material may enter and jam within the lumen, but vesselwall may not extend sufficient close within the lumen of the aspirationcatheter, and therefore changing impedance in a predictable and usefulmanner.

FIGS. 58B and 58C illustrate examples in which multiple impedanceelectrodes 5860 on one side distributed at different longitudinalpositions along the inner wall of one side of the aspiration catheter5800 lumen. In FIG. 58B, this may allow individual position signals tobe taken using the individual electrodes 5860 of the array of electrodesand a single reference electrode 5860. Alternatively, FIG. 58C shows anexample in which both side of the lumen of the aspiration catheter 5800include multiple electrodes 5860, 5860′, allowing further refinement ofthe longitudinal position of the occlusion (e.g., clot) within thelumen, and/or helping to distinguish clot material from vessel wallbased on the signal and/or the location of the signal(s) when used.

Also described herein are methods of using an apparatus as describedherein to perform a pulmonary embolectomy. In this example, theaspiration catheter is advanced through the pulmonic valve, bend or turninto the pulmonary artery to where a clot may be positioned. In someexamples the aspiration catheter may be passed through an access vein(such as the right subclavian vein or jugular vein) into the superiorvena cava through the right atrium through the tricuspid valve, throughthe right ventricle, and through the pulmonic valve, to a putative clot(thrombus or occlusive embolus) situated in the pulmonary artery orbranches of the pulmonary artery, such as the left pulmonary artery orthe right pulmonary artery. In practice, it has proven particularlydifficult to capture clot from the left pulmonary artery by aspirationas the navigation required may tend to drive the tip of the aspirationcatheter into the wall of the vessel, which is difficult or impossiblefor most devices to distinguish from clot.

The method may further include applying aspiration (e.g.,suction/negative pressure). If the aspiration catheter is occluded,e.g., so that flow through the suction catheter is occluded, theapparatuses described herein may distinguish between occlusion by clotmaterial and occlusion by the vessel anatomy (e.g., vessel wall, valve,etc.). The apparatus may output this information (e.g., occlusionidentity information), which may be used by the apparatus to determinehow to proceed with the method, including automatically proceeding ormanually proceeding. In some cases the information may be used totrigger a clot extraction response if the obstruction is clot material.In some examples this information may be used to control the aspiration(suction) by increasing or modifying the suction if the occlusion is aclot material or turning off aspiration if the clot material is vesselanatomy. In some examples the apparatus may emit an output (e.g., alert)that the occlusion is clot material, or that the occlusion is vesselanatomy.

The apparatus may distinguish between clot material and vessel anatomy(e.g., vessel wall) by any of the techniques described herein. In someexamples the apparatus may distinguish between clot material and vesselanatomy based on an intraluminal sensor at a predefined location withinthe lumen of the aspiration catheter. For example, the apparatus maydetermine that the occlusion material is clot material or vessel wall bydetecting deflection of a deflectable member at a predetermined locationwithin lumen of the vessel.

Any of the methods (including user interfaces) described herein may beimplemented as software, hardware or firmware, and may be described as anon-transitory computer-readable storage medium storing a set ofinstructions capable of being executed by a processor (e.g., computer,tablet, smartphone, etc.), that when executed by the processor causesthe processor to control perform any of the steps, including but notlimited to: displaying, communicating with the user, analyzing,modifying parameters (including timing, frequency, intensity, etc.),determining, alerting, or the like.

It should be appreciated that all combinations of the foregoing conceptsand additional concepts discussed in greater detail below (provided suchconcepts are not mutually inconsistent) are contemplated as being partof the inventive subject matter disclosed herein and may be used toachieve the benefits described herein.

EXAMPLES

As described above, any of the methods and apparatuses described hereinmay be used to detect and monitor (e.g., track) material, including clotmaterial, within the lumen of the suction catheter. For example, aplurality of sensors (e.g., internal sensors) may be arranged along thelength of the lumen extending proximally, allowing tracking of clotmaterial as it passes through the lumen. The controller of the apparatusmay transmit, store, analyze and/or output (e.g., display) the trackingand/or detection of material within the lumen of the suction catheter.These methods and apparatuses may improve remove of obstructive materialfrom the vasculature by aspiration.

As described above, the use of large bore aspiration catheters to removeobstructive material from a blood vessel has been found effectiveespecially within the venous vasculature. Current technologies havelimitations that increase the time of the procedure and present a safetyrisk of damaging the vessel walls of the vasculature. Obstructivematerial (e.g., clot) within the venous vasculature that needs to beremoved may be larger in cross sectional area than the cross-sectionalarea of the catheter used to access the obstructive material. Forexample, thrombus from a peripheral vein in the leg that dislodges andpasses into the pulmonary arteries may obstructs blood flow though thepulmonary arteries. Such thrombus material can be approximately 10-20 mmin diameter and can be approximately 100 mm long, or longer. When thethrombus is dislodged, the thrombus is carried by the blood going to thelungs and the thrombus may become wedged within the pulmonary arteriesas the arteries begin to narrow and branch into the segments of thelungs. Once wedged, the dislodged thrombus may straddle multiple vesselsof the pulmonary arteries or may be balled up and occlude a mainpulmonary artery. Venous thrombus is comprised of mainly red blood cellsand fibrin formed under low wall shear rates, giving the thrombi uniquematerial properties allowing the thrombus to be compressed and elongatedwithout easily tearing apart. The material properties of the thrombusenable the large pieces of thrombus to be removed from the vasculaturethrough a smaller catheter. Current aspiration catheter technologiestypically rely on the compressibility of the thrombus and highaspiration flowrates created, e.g., by ultra-high vacuum pressures(e.g., <−700 mmHg) to pull the large mass of thrombus through thesmaller aspiration lumen which frequently causes the thrombus to getstuck within the aspiration lumen of the catheter or, even riskier, maycause the vessel to collapse and the aspiration forces of the catheterto be applied to the thin wall of the vessel; the user typically has noway to assess if either event, or which of these events, is happening.Instead, all the user may see is that aspiration has been applied andthere is minimal to no blood movement coming back through the catheter.Users will typically wait to see if the thrombus continues to compressso that it can eventually be pulled through the catheter. While theywait, the user may attempt to increase the vacuum within the aspirationlumen multiple times. This process can take several minutes and oftenresults in no change, forcing the user to retract the catheter proximaland attempt to pull the potentially stuck thrombus with the catheteruntil the thrombus tears and blood flow starts to rush into theaspiration source. In some instances, the catheter must be completelyretracted across the heart and pulled out of the body of the patientrequiring the user to start the procedure over, meaning that the usermust re-cross the heart and regain access to the pulmonary artery thatwas being treated. The additional time and steps required increase therisks of the procedure. Thus, it may be particularly beneficial toprovide systems and methods for removing of obstructive material thatenable the user to know what is happening in front of and/or within aninternal lumen (i.e.: aspiration lumen) of a catheter.

The methods and apparatuses described herein may permit the user tomonitor and/or track clot material within the lumen of the suctioncatheter, including identifying that clot material (or in some casesvessel wall) is clogged, and/or where it is clogged. The apparatus andmethods may also allow the apparatus to distinguish between clogging ofthe vessel, which may be cleared mechanically, and/or by modulating,including increasing, the applied suction and collapse of the vessel,which may instead require decreasing the applied suction. In general,these methods and apparatuses may decrease the time and risk associatedwith removing thrombus from a blood vessel.

For example, these methods and apparatuses, including suction catheters,may detect the presence of thrombus within a lumen of the catheter,measure at least one fluidic parameter of the lumen of the catheter(e.g., flow rate, etc.), may estimate the volume of thrombus withinand/or passing of clot material and/or blood through the lumen of thesuction catheter, and may indicate this data to the user, store and/ortransmit the data. In some examples the apparatuses and methodsdescribed herein may detect when an opening into the suction catheter(e.g., the aspiration orifice) is sucking onto a vessel wall and/or whenthe apparatus is clogged with clot material.

FIGS. 59A-59B illustrates one example of an apparatus as describedherein. In this example, the apparatus includes a catheter 5900 having adistal 5901 and a proximal end 5902 with a flexible body 5903 extendingbetween the ends. An internal (e.g., suction) lumen 5904 extending alongthe length of the catheter. At least one electrical property sensor(e.g., impedance sensor) having a least one conductive surface, and insome examples, preferably two conductive surfaces, is positioned withinthe lumen and configured to contact a material (e.g., blood, clot, etc.)within the lumen. As described above, e.g., FIGS. 1A, 1I, 12, and15-18E, multiple sensors (including surface electrodes) may be used. InFIG. 59 , the sensor(s) include two conductive surfaces that arespatially positioned relative to each other such that the impedance ofthe substance contacting both surfaces can be measured and processed todetermine contact with a clot material or other material within ehlumen. The conductive surfaces of the sensing element can be spatiallyaligned radially around the circumference of the internal lumen 5904and/or axially aligned along the longitudinal axis of the internal lumen5904) as shown herein. In this example, three sets of electrical (e.g.,impedance) sensors are positioned longitudinally along the length of thelumen. The distal sensor (including a first sensing electrode 5905 and asecond sensing electrode 5905′) includes two conductive surfaces eachmade of a conductive material such as stainless steel, extendingradially at least partially around the lumen of the suction catheter,e.g., extending between about 10-360 degrees (e.g., between about20-360, between about 30-360 degrees, between about 40-360 degrees,between about 45-360 degrees, between about 60-360 degrees, more than 10degrees, more than 20 degrees, more than 30 degrees, more than 45degrees, more than 50 degrees, more than 60 degrees, more than 70degrees, more than 80 degrees, more than 90 degrees, etc.) of the innerdiameter of the lumen. The electrode sensor may be affixed to the bodyof the catheter so that the inward facing surface is exposed to theobjects that pass through the internal lumen 5904 of the catheter. Theconductive surfaces may form a continuous surface or may be discretesurfaces that are electrically connected as a single sensing electrode.In FIGS. 59A and 59B the sensing electrodes forming the sensors may beformed, e.g., of a continuous strip of conductive material that isapproximately 1 mm wide by about 0.13 mm thick curved strips or bands,forming complete or partial rings extending around the lumen of theapparatus, including at the distal end (e.g., the distal end region, insome examples, the extraction zone). FIG. 59B shows a cross-sectionthrough the suction catheter of FIG. 59A. In this example, the sectionshows a suction lumen 5904 as well as a guide wire lumen 5933 and anavigation lumen 5934.

As used herein, a ring sensor electrode (“ring electrode” or “ringsensor”) may extent fully, or partially, around the inner wall of thesuction catheter lumen. Thus, in some examples the ring may be anannular ring or rings that are longitudinally arranged and may be eithercontinuous (as shown in FIG. 59A), or may be discrete (see, e.g., FIGS.11 and 12 ).

For example, in some variations the ring electrodes may be split andpressed outwardly into the inner lumen of the catheter. The surfaces ofthe ring electrode can be thermally embedded or chemically bonded to theinner surface of the lumen. In some examples, small insulated conductivewires may be mechanically affixed to each one of the conductive surfacesusing a joining method such as soldering. The insulated conductive wiresmay run throughout the length of the lumen and into the handle 5908 ofthe catheter. In FIG. 59A, the apparatus includes three sets (e.g.,pairs) of sensing electrodes, one each at the distal 5905, 5905′,proximal 5908, 5907′ and at least one intermediate region 5906, 5906′.In some embodiments, conductive wires can continue out of the handle5908 and attach to an external signal processing source. In this examplethe signal processing source 5909 may include a small battery poweredPCB encapsulated in the handle 5908 that is connected to an LED 5910 anda digital display 5911. The distal sensing electrodes 5905, 5905′ may bedistally positioned just proximal to the distal end 5901, e.g., up to 5mm proximal to the distal opening, which may be a tapered or lateral(side-facing) suction opening in any of these suction catheters. Insuction catheters including a tapered or slanted distal end, the distalpositioning may be relative to the proximal edge of the distal end 5901of the apparatus, as shown in FIG. 59A. The conductive surfaces of thesensing electrodes (ring electrodes) in this example may be spaced adistance of about 1-20 mm apart, preferably about 2-5 mm apart(edge-to-edge). The spacing of these surfaces may be selected to ensurethrombus passing through will bridge across the conductive surfaces, andto allow for multiple sampling points during contact as the thrombuspasses through the lumen. The distal sensor (including sensingelectrodes 5905, 5905′) may be distally positioned relative to thedistal end 5901 so that it may rapidly detect substances entering theinternal lumen 5904, and not substance (e.g., clot) touching just, orstuck to, the distal end 5901 of the catheter. The second electricalsensor (including electrodes 5906, 5906′) can be axially positionedalong the internal lumen 5904 between the distal 5901 and proximal 5902ends of the catheter. In this example, the second sensor may bepositioned, e.g., between about 2-80 cm, preferably about 30 cm,proximal from the distal end 5901 of the catheter. This distance may bepreferred as the thrombus passing through the lumen may be moving at aconstant velocity when being extracted completely out of the catheter.This distance may also be preferred in some embodiments because it mayposition the electrical sensors in a portion of the catheter that isproximal to the tortuous anatomy such as when accessing and treating thepulmonary vasculature. In some use scenarios of this invention, the usercould use this sensing element as an indicator to stop aspiration powereither allowing momentum to continue passing the thrombus through thelumen or to allow the thrombus to reside in the lumen while going aftermore obstructive material. As described above, this may be useful tominimize the blood loss during a procedure. The conductive surfaces ofthe second electrical sensor (e.g., electrodes 5906, 5906′) in thisexample may be constructed similarly to the distal sensor (e.g.,electrodes 5905, 5905′) also shown as spaced about 2-5 mm apart.Insulated conductive wires may run proximally from the sensors and maybe attached to the same signal processing source 5909, e.g., in thehandle 5908. The proximal electrical sensor 5907 is positioned betweenthe second electrical sensor 5906 and the aspiration source (not shown)of the device. In this example the proximal sensor (electrodes 5907,5907′) is positioned just distal to the proximal end 5902 of thecatheter within the internal lumen 5904. The proximal sensor positionedin this location may detect when the obstructive material (e.g., clot)has cleared the internal lumen 5904 of the catheter and may allow foranalysis of material with the distal and second sensing elements todetermine mechanical properties of the obstructive material such as massand volume as well as the mechanical performance of the catheter such asflow rate of material (e.g., clot) through the apparatus. The conductivesurfaces of the proximal sensor (e.g., of electrodes 5907, 5907′) may beconstructed identically to the second sensor (electrodes 5906, 5906′)and may be connected to the signal processing source 5909.

FIGS. 60-63C illustrate examples of electrical sensors as describedherein, including in particular sensors comprising annular ringelectrodes. For example, FIG. 60 shows an example of an apparatus (e.g.,system) including an embolectomy catheter having an elongate tubularcatheter body 6004; an internal lumen 6006 through which bio-fluids orother materials may pass, such as blood, and/or solid or semi-solidmaterial, such as a blood clot; a pair of electrically conductiveelectrodes 6005, 6005′ configured to be substantially in contact withsaid bio-fluid within the lumen; and an alternating electrical powersource (AC Voltage) 6008 configured to establish and control a variablevoltage between these sensing electrodes, and further configured tosense and measure and record the electrical impedance between saidelectrodes over time. In this example the electrodes 6005, 6005′ mayoperate as an electrode pair, forming an electrical sensor, and may beconfigured with a known and fixed distance between the electrodes, asmeasured in the axial direction of the catheter, of between about 0.5 mmand 20 mm, and more preferably between about 1 mm and 10 mm, e.g.,between about 2 mm and 5 mm. The electrode pair may be furtherconfigured to be located proximal to the open entrance of the catheter,preferably between 0 mm and 20 mm from said open entrance measured inthe axial direction of the catheter, or more preferably between 1 mm and10 mm from said catheter open entrance.

The system of FIG. 60 is configured to allow for the electricalimpedance to be measured in the internal lumen of the catheter proximalto the electrode pair to detect changes in contents flowing through thecatheter over time. Specifically, the system may allow for the detectionof changes in material density, composition, and other properties thatresult in measurable changes in electrical impedance, such as thepassage of a blood clot. The apparatus may be configured to detectimpedance from the sensor electrodes, including magnitude and/or phase,at different frequencies.

FIG. 61 shows an example of a pair of electrically conductive electrodes6105, 6105′ shown configured as two electrically conductive annularrings through which a material may pass. The electrodes may be connectedto a variable power source 6108, such as to an AC voltage, AC current,or other electrical configuration that changes the voltage and/orcurrent between said electrodes over time. The variable power source isfurther configured to measure and record the electrical impedancebetween the two electrodes 6105, 6105′. In this example the electrodesmay primarily measure fluid impedances in the axial space between thetwo annular electrodes.

In one example, as shown in FIG. 62 , the embolectomy catheter apparatus(e.g., suction catheter) may include a tubular catheter body 6204; aninternal lumen 6206 through which bio-fluids or other materials maypass, such as blood, and/or solid or semi-solid material, such as ablood clot; a distal pair of electrically conductive electrodes 6205,6205′ configured to be substantially in contact with said bio-fluid andlocated proximal to the open entrance of said catheter; a proximal pairof electrically conductive electrodes 6207, 6207′ configured to be afixed distance from said distal electrode pair, as measured in the axialdirection of the catheter, and in contact with the bio-fluid. Theapparatus may also include a first alternating electrical power source(e.g., AC Voltage) 6208 configured to establish and control a variablevoltage between said sensor (e.g., distal electrodes 6205, 6205′), andfurther configured to sense, measure and record the electrical impedancebetween said electrodes of the distal electrode pair over time. Theapparatus may also include a second alternating electrical power source6208′ (e.g., AC Voltage) configured to establish and control a variablevoltage between said proximal electrodes of the proximal electrode pair.The apparatus may also be configured to sense and measure and record theelectrical impedance between said proximal electrodes over time.

In the example shown in FIG. 62 , the suction catheter may be configuredto make impedance measurements at the distal 6205, 6205′ and proximal6207, 6207′ electrode pairs, allowing the system to cross-correlate thesignals to determine flow characteristics such as: flow velocity: thesize and/or volume of a blood clot flowing through the catheter, etc.

During normal catheter use the catheter tip at the location of thesuction opening of the catheter may become occluded by venous tissueform the surround blood vessel wall, blocking flow and resulting in someamount of tissue entering the open entrance region of the catheter. Inthis condition the distal electrode pair may detect a characteristicchange in impedance indicative of this venous wall material entering thecatheter, and the system may supply the physician with this informationin real time.

FIGS. 63A-63C show another example of a set of electrodes forming anelectrical sensor of a suction catheter, in which the electrodes 6305,6305′ are configured as partial annular segments which are substantiallyring-like. As mentioned, in any of these examples the ring electrodesmay extend just partially around the annulus of the suction lumen. Forexample, FIG. 63B shows an example in which the pair of electrodes6305″, 6305′″ forming an electrical (e.g., impedance) sensor areconfigured as plate-like structures that extend just partially (e.g.,between about 30-50 degrees) around the lumen and may be mounteddiametrically opposing one another on internal surface of the catheterwall. In this example, the electrode pair may measure the electricalimpedance across the catheter lumen when connected to a variableelectrical power source. The electrodes 6305″, 6305′″ may be configuredas a set of two electrodes, as a set of three electrodes, or as a set ofany number of electrodes. Furthermore, multiple sets of annular segmentelectrodes may be employed at locations along the length of the catheterto measure and record additional flow characteristics such as flowvelocity, size and mass of blood clots etc.

FIG. 63C shows an alternate example of an electrical (e.g., impedance)sensor for a lumen of a suction catheter. In this example, the electrodepair includes electrodes 6315, 6315′ that are configured as helicalconductive elements, with overlapping helical pitches such that that theresulting electrode pair behaves substantially as an annular ring pair(with the two electrode elements axially adjacent to one another) and asan annular segment pair (with the two electrodes diametrically adjacentto one another). These electrodes may be mounted on the internal surfaceof the catheter wall, in contact with the internal bio fluid within thecatheter. Helical electrodes may be connected to a variable electricalpower source (as described above) and may be configured to measure andrecord electrical impedance of the internal flow within the catheterover time. These helical electrode pairs may be located at any axiallocation in the catheter and the catheter system may be configured withone, two or a plurality of electrode pairs at different locations alongthe axial length of the catheter to measure and record additional flowcharacteristics such as flow velocity, size and mass of blood clots etc.Both the ring electrodes shown in FIGS. 63A-63B, and the helicalelectrodes shown in FIG. 63C are examples of annular electrodesextending radially around the suction lumen.

FIG. 64 illustrates an example of an output of an apparatus such as theapparatus shown in FIG. 62 , illustrating the impedance output over timeof a distal sensor, comprising a first pair of distal internal ringelectrodes (that extend about almost completely around the lumen and areseparated from each other by between about 5 mm), and a second pair ofproximal ring electrodes (that extend almost completely around the lumenand are separated from each other by between about 5 mm). As shown inthe graphs, the trace from the distal sensor (sensing electrode pairs)6455 show an initially low impedance (in Ohms) that rises dramaticallyas thrombus enters the internal lumen at about 11.75 seconds and isinitially held-up in the distal end region so that the impedance signalremains high as thrombus is pulled into the lumen 6457. The proximalsensor (sensing electrode pairs) 6459. At about 12.75 seconds, the firstsensor at the distal end region shows a rapid rising and falling of theimpedance, indicating that the clot material is breaking up within theinternal lumen of the catheter 6461. After a brief time period (e.g.,approximately 0.6 seconds) the proximal sensor (sensing electrode pairs)signal shows a similar impedance fingerprint 6463 for the thrombusmaterial as it passes out of the lumen of the catheter. As shown fromthe sample data of FIG. 64 , these apparatuses may detect the presenceof clot material within the lumen of the catheter and based on thedifferential timing 6466 of the signal between the distal sensor andproximal sensor signals (e.g., 0.6 s) the rate of travel of the clotmaterial down the known length of the catheter may be estimated andpresented. In addition, this data may also be used to determine theapproximate size of the clot material. For example, the length of thethrombus may be estimated based on the size (in time) 6468 of theproximal signal and the rate of travel of the clot through the catheter(based on the time between similar signals from the distal sensor to theproximal sensor 6466 and the length of the catheter lumen).

FIG. 65 shows another example of an apparatus as described herein,including a catheter (e.g., aspiration catheter) 6500 for removingmaterial from within a blood vessel, a vacuum/suction subsystem 6519(e.g., including a vacuum/suction pump, filter(s), etc.), and acontroller 6515 for receiving sensor data from the aspiration openingsensor(s) 6558 and/or the internal sensors 6505, 6505′, 6507, 6507′,6509, 6509′. In FIG. 65 the aspiration opening sensor 6558 may includetwo or more (e.g., a pair) of electrodes on or adjacent to the rim ofthe aspiration opening 6521. For example the electrodes forming theaspiration opening sensor may be recessed slightly into the aspirationopening, or they may be on the rim of the aspiration opening (flush,recessed into the rim, or extending proud of the rim). In FIG. 65 only asingle electrode is shown. The aspiration opening is on a lateral sideof the catheter. Three internal electrical impedance sensors are shown.For example, a first internal electoral impedance sensor includes afirst set 6505, 6505′ of electrodes is shown at a distal end region(e.g., near or adjacent to the aspiration opening sensor) comprising apair of annual electrodes, expending partially or fully around the innerdiameter of the suction lumen, as described above. A second internalelectrical impedance sensor is shown comprising a second pair 6507,6507′ of annular electrodes expending partially or fully around theinner diameter of the suction lumen, about midway along the catheter(note that FIG. 65 is not shown to scale). A third internal electricalimpedance sensor having a second set of annular electrodes 6509, 6509′is shown in FIG. 65 . More or fewer internal electrodes may be included.The flexible elongate catheter 6500 has a suction lumen 6513 extendingtherethrough and the internal electrical impedance sensors are allwithin the suction lumen.

In FIG. 65 , the controller 6515 may be coupled to the internalelectrical impedance sensors and to the aspiration opening sensor. Thecontroller may also include or be coupled to a power source for applyingenergy to the internal electrical impedance sensors and to theaspiration opening sensor. For example the controller may control theapplication of an alternating current between the two or more electrodesof each sensor. Each sensor may be separately energized, or energy(e.g., alternating current) may be applied to all or a subset of thesensors together. The controller may be configured to apply a singlefrequency or a plurality of frequencies, (e.g., between 1 Hz and 5 MHz,e.g., between 100 Hz and 3 MHz, etc.). The internal electrical impedancesensors and to the aspiration opening sensor may be used to determine animpedance spectrum using multiple different frequencies. The frequencyof alternating current applied to the internal electrical impedancesensors may be the same or different from the frequency applied betweenthe electrodes of the aspiration opening sensor. In general, thecontroller may receive signals (e.g., impedance signals) from theinternal electrical impedance sensors and to the aspiration openingsensor and may store, analyze and/or transmit the electrical signals(impedance signals). For example, the controller may detect anobstructive material (e.g., clot) within the suction lumen based onelectrical impedance signals from the internal electrical impedancesensor.

In any of the apparatuses described herein the internal electricalimpedance sensors and the aspiration opening sensor may be connected viaone or more wired or wireless connections to the controller 65015. Forexample, in FIG. 65 the apparatus including a conductive trace (e.g.,wire, etc.) extending from each electrode of the internal electricalimpedance sensors and the aspiration opening sensor to a connector 6587.The connector may couple directly or indirectly to the controller 6515.In some examples the catheter apparatus may include circuitry toprecondition the signals from the internal electrical impedance sensorsand/or the aspiration opening sensor. For example, the catheterapparatus may include circuitry to amplify, filter and/or combinesignals from the internal electrical impedance sensors and/or theaspiration opening sensor. In some examples the circuitry may be part ofthe connector 6587.

In the example apparatus shown in FIG. 65 , the suction lumen 6513 ofthe apparatus 6500 may couple to the vacuum subsystem 6519 and/or maycouple 6538 to a guide channel or navigation channel (not shown), asdescribed above.

Although FIG. 65 is described with three separate internal electricalimpedance sensors and an aspiration opening sensor, in some examples theelectrodes forming these sensors may be shared between the differentsensors (e.g., current may be applied to a first electrode of the distalinternal electrical impedance sensor and impedance may be measured fromone or more electrodes of the second internal electrical impedancesensor and/or the third internal electrical impedance sensor.Alternatively or additionally, the signals may be applied and sensedbetween just the subset of electrodes forming the internal electricalimpedance sensors and/or the aspiration opening sensor.

The internal electrical impedance sensors described herein, such asthose shown in FIG. 65 , may be used to reliably and robustly detectobstructive material, such as clot material or vegetation, from withinthe suction lumen of the aspiration catheter. The impedance measurementsmay also be used to track movement of the material within/through thelumen (including but not limited to rate of movement), detect ordetermine blockage of the suction lumen, and/or to determine an estimateof the amount of material passing through the suction lumen (e.g.,removed from the vessel), and may determine how disrupted the materialis.

FIG. 66 illustrates one example showing the detection and/or tracking ofclot material through the lumen of an aspiration catheter similar tothat shown in FIG. 65 , including three sets of internal electricalimpedance sensors (distal tip, mid and proximal). The internal electrodesensors each included a pair of annular electrodes that extend partiallyaround the lumen of the suction catheter. The controller was configuredto sense Vrms using an AC frequency initially set to 1 MHz. A sampleblood clot in saline was aspirated through the aspiration opening a thedistal end of the catheter and impedance of each internal electricalimpedance sensor (e.g., across each pair of electrodes forming thesensor) was detected. In this example, the distal internal electricalimpedance sensor included a pair of annular electrodes that were spacedapproximately 2.5 mm from the proximal end of the aspiration opening,and were separated from each other by approximately 3 mm. The catheterhad an inner diameter of approximately 0.275″. Repeated testing showed a100% success rate in detecting an tracking clot material through theaspiration catheter. In FIG. 66 , an exemplary trace shows the impedancesignal detected at the first internal electrical impedance sensor 6605,which first detected clot material near the first internal electricalimpedance sensor beginning at a start time 6606, and lasting for a firstduration 6607. The impedance signal for the second internal electricalimpedance sensor 6617 at the middle region of the catheter also showeddetecting of the impedance signal indicating the clot material at astart time 6618 (showing some fragmentation of the clot, as a rise andfall of the impedance over time). Finally, the third internal electricalimpedance sensor showed impedance signal 6629 indicating the presence ofclot material at the proximal end of the catheter, beginning at a starttime 6630. The controller may use these impedance signals to track themovement of obstructive material through the lumen of the catheter,including determining an estimate of the rate of movement through thelumen. In this example, the positions of the internal electricalimpedance sensors is known, and the impedance measurement of eachinternal electrical impedance sensor may be used to determine the startof the passage of the material near each internal electrical impedancesensor. As is apparent in FIG. 67 , the characteristic shape of eachimpedance measure (at 1 MHz in this example) may be correlated toconfirm that a particular material is passing by each internalelectrical impedance sensor. The number of peaks from the impedancesignal, as well as the change in spacing between the peaks, may also beused to determine disruption (e.g., fragmentation) of the material. Thecontroller may also detect, based on a threshold for the impedancesignal, the start (e.g., when clot material begins passing through thelumen), the rate of material through the lumen and/or the finish, whenclot material has completely passed through the lumen. The controllermay also sense blockage of the lumen based on the impedance signal. Thecontroller may control the operation of the suction to increase/decreaseand/or turn on/off suction based on the impedance signals from theinternal electrical impedance sensors. For example if clot material ismoving slowly through the lumen the suction may be increased (orconversely decrease if clot material is moving too quickly, which mayincrease undesirable blood loss). The controller may also turn off orreduce suction when no more clot material is detected, e.g., at theproximal internal electrical impedance sensor.

The apparatus shown in FIG. 65 (similar to those also described in FIGS.1A-1D, 2-13, 20-23, 27A, 39B, 45-46B, 47 ) may also include anaspiration opening sensor to detect when an obstructive material is ator near the aspiration opening. The impedance-based aspiration openingsensors described herein may be used with the application of force(e.g., by driving the aspiration opening against the material and/orwall) to more clearly detect and distinguish between target material(e.g., clot material) and non-target material (e.g., vessel wall). Thus,any of these apparatuses may be configured (e.g., the controller may beconfigured) to detect clot material when force is being applied at theaspiration opening. In any of these examples the force applied may besuction (e.g., aspiration) applied through the aspiration opening. Thus,in any of these apparatuses the controller may determine when a force(e.g., a threshold valve for the force) is being applied and may analyzethe resulting signal from the aspiration opening sensor only while thisforce is being applied. For example, in any of these examples controllermay analyze the signal (e.g., impedance signal or other signal) from theaspiration opening sensor when the pressure within the lumen (andtherefore at the aspiration opening) is above a minimum thresholdindicating that the aspiration opening is being held/driven against anocclusion (clot, wall, etc.) within the vessel. Surprisingly, theresulting aspiration opening sensor signal may be more reliable duringthis period, perhaps because the force applied may prevent more than onematerial (e.g., wall and clot, or clot and blood, or wall and blood orwall, clot and blood) from being present in close proximity to theaspiration opening sensor. Thus, the resulting signals from theaspiration opening sensor may be more characteristic of either clot,wall or blood, rather than being a combination of these signals.

The methods described above may be used with virtually any type ofsensor, including the electrical (e.g., impedance) sensors illustratedabove. In general, the methods and apparatuses may include the use oftechniques for identifying the type of tissue (e.g., clot, vessel wall,or blood) which may be sensed and classified when sampling from the tipof an aspiration lumen as part of a thrombectomy procedure, e.g., for apulmonary embolism. As described above, these techniques may includeelectrical impedance, electrical capacitance (e.g., transient electricalresponse), ultrasound, optical transmission (e.g., spectroscopy),optical reflectivity, inductive coupling, mechanical deflection, thermalconductivity and elasticity.

For example, electrical impedance may be sensed between two or moreelectrodes located at the orifice of the aspiration lumen. Thiselectrical impedance may be used to differentiate tissue type and may bemeasured at different frequencies (e.g., between about 100 Hz to about10 MHz) using alternating current (e.g., sinusoidal, sawtooth, squarewave, etc.). One single frequency or several frequencies may be used,including a spectrum of frequencies. In any of the impedance techniquesdescribed herein, the amplitude and phase of the response may bemeasured to fully characterize the impedance of the load seen betweenthe electrodes. In some examples, just the magnitude may be used. Theeffective resistance, capacitance and/or inductance of the tissue may becalculated at each frequency and compared to known thresholds tocategorize the tissue as either clot, vessel wall, or blood. Thesethresholds may be different depending on the size and spacing of thesensing electrodes.

In any of these apparatuses and methods, the sensing electrodes mayeither be located at the edges of the orifice (e.g., the rim) or justslightly inside the lumen facing internal to the shaft, e.g., recessedfrom the rim into the suction lumen. Separately the one or moreelectrodes may be recessed into the material forming the rim, and/or thewall of the lumen, or they may be flush with or may extend proud of therim or wall. Preferably, the electrodes may be recessed somewhat and maybe internally facing electrodes in order to help ensure the measuredtissue is just the desired specimen and not other material nearby. Forexample, FIG. 67 illustrates one example of a distal end of a catheterhaving a distal-facing opening 6721 forming the aspiration opening witha pair of electrodes 6758, 6758′ on the rim. The aspiration openingopens into the suction lumen 6713.

In any of the methods an apparatuses described herein a second sensormay be used in conjunction with the aspiration opening sensor to detectand/or identify clot material or to distinguish clot material fromvessel wall and/or blood. For example in FIG. 68 the apparatus includesan aspiration opening 6821 with an aspiration opening sensor including apair of electrodes 6809, 6809′ at the distal end. The apparatus alsoincludes an internal impedance sensor comprising a pair of sensingelectrodes 6807, 6807′ that are positioned just proximal of theaspiration opening in FIG. 68 ; alternatively, they may be within thelumen and opposite of the aspiration opening in variations in which theaspiration opening is on a slide of the catheter. Thus, in some examplesthe apparatus may use electrical impedance with a second set ofelectrodes, as shown in FIG. 68 . For example, the controller mayinclude information from the internal sensor as an independent measureto confirm whether the apparatus (e.g., when force is applied to thetip, e.g., such as by applying suction to the aspiration opening fromthe suction lumen) is in contact with a vessel wall or a clot material.This second pair of electrodes may be used to measure impedance a bitfurther into the aspiration lumen, and if the material in contact withthe aspiration opening shows a large change at those sensors it may bemore likely to be clot material, vs. vessel wall which cannot penetratethat deeply down the aspiration lumen even under negative pressure.

In any of these apparatuses and methods a transient electrical responsemay be used to help identify the type of material in contact with theaspiration opening. For example, the electrical properties of the tissuespecimen between the sense electrodes described above may also beevaluated using a square-pulse and measuring the transient response ofthe electrode-tissue interface. This is illustrated in FIGS. 69A and69B. The rise-time of voltage when exposed to a square pulse through aseries resistor may be used to quantify the effective capacitance of theelectrode-tissue interface, which is another possible differentiatingproperty between tissue types. In FIG. 69A the example circuit schematicshows an applied square wave pulse that is applied across the sensingelectrodes and a voltage measured (Vmeas). The time constant for therise time and/or the time constant for the falling time (shown in FIG.69B) when a square wave pulse is applied may be analyzed, as shown inFIG. 69B. The time constant(s) may be characteristic of the materialbeing examined, e.g., clot material, blood and/or vessel wall.

Alternatively or additionally, in some examples an ultrasound transducermay be used to characterize material at the aspiration opening. Forexample, as shown in FIG. 70 , a pair (or more) of piezoelectrictransducers 7028 may be used to discriminate between tissue types at ornear the aspiration opening 7021 (opening into the suction lumen 7013)by either looking at: acoustic impedance in continuous-wave mode, orperformance a discrete ping on one transducer and measure the responseon another, looking at amplitude. For example, the controller may checkthe response amplitudes vs. thresholds for each tissue type (e.g.,blood, clot, vessel wall). As shown, the transducers may be placed atthe tip of the catheter on either side of the aspiration opening.

FIG. 71 schematically illustrates an example of a catheter including asuction lumen 7213 in which optical transmission/spectroscopy may beused to determine and/or confirm the presence of a particular type ofmaterial (blood, vessel wall, clot, etc.) at the aspiration opening 7121of the catheter. For example, the optical transmission properties of thetissue types may be another way to discriminate them from each other.Specifically, if an LED or other light source 7138 is placed at the tipof the catheter, and an optical detector 7139 may be positioned at thetip of the catheter on the opposite side from the emitter 7138, thedetector 7139 can receive the optical signal from the source, altered bythe transmission properties of the material in between the two (e.g.,against the aspiration opening). This can be done at one frequency or aspread of different electro-magnetic frequencies to obtain spectroscopyinformation about the optical transmission characteristics of the tissuesample. The tissue types may then be categorized by thresholds in thetransmission properties at certain frequencies.

FIG. 72 illustrates a similar configuration using opticalreflectivity/spectroscopy. In this example the catheter includes anaspiration opening 7221, opening into a suction lumen 7213, and theoptical reflective properties of the tissue types may be used todiscriminate them from each other. For example, an LED or other lightsource (emitter 7238) may be placed at the rim (or within the rim) ofthe aspiration opening, and may be integrated with an optical detector7239 also placed at or on the rim of the aspiration opening near thethat emitter (LED or light source), and the optical reflectiveproperties of the material in front of this sensor may be used tocharacterize the material. One or more of these light sources/sensors atthe tip of the catheter may be used to determine the average “color” ofthe material in front of the orifice. In some examples one frequency, aspread of several frequencies, or a broad spectrum of frequencies may beused look for the reflected amplitudes. The type of the material maythen be determined based on categories by thresholds of the reflectiveproperties at certain optical frequencies.

FIG. 73 illustrates an example of a catheter including an aspirationopening sensor that is configured as an inductive coupling coefficientsensor. For example, the inductive coupling coefficient may be used todifferentiate between tissue types based on the degree to which tissuealters the coupling coefficient between two inductive coils 7328, 7328′placed, e.g., near the tip of the catheter (e.g., on either side of theaspiration opening 7321 into the suction lumen 7313). The couplingcoefficient between the coils (which may be based on the originaldesigned geometry) may change when different materials are placed inbetween them. Thus, the coupling coefficient may be measured andthresholds in this value may be used to differentiate types of material.The construction of these coils may be embedded as traces in a flexboard that wraps around the end of the catheter.

Any of the apparatuses and method described herein may alternatively oradditionally use thermal conductivity to help identify the materialadjacent to (and/or in contact with) the aspiration lumen. Thermalconductivity can be used to differentiate material types at the end ofthe catheter by determining the degree to which that material conductsheat. For example, as shown in FIG. 74 , a heat source 7428 such as aresistor may be used at the end of the catheter and one or more heatsensitive elements 7329 such as a thermistor or thermocouple may be usedto measure the temperature of a nearby location, which requires the heatto traverse through the unknown material. For example, the heat source7428 and heat sensor 7429 may be part of the aspiration opening (or justrecessed relative to the aspiration opening 7421 into the suction lumen7413. The thermal conductivity may be measured to see how quickly thetemperature is able to increase when a heat source is started. Thisthermal conductivity may be used to characterize which type of material(e.g., blood, clot material, vessel wall) is in between the heat sourceand the temperature sensor.

Alternatively or additionally, the elasticity of the material at theaspiration orifice may be used to identify the material. For example,the elasticity of the material may be used to discriminate among blood,clot, and vessel wall based on the amount of force that material pushesback when faced with an impinging force. Pressing into the material witha known force (either spring force or air or saline) and measuring theamount of force pushed back by the material may discriminate between thetissue types, in part because the different materials (blood, clot,wall) may be a liquid, a gel, and a fibrous solid, which have verydifferent properties of elastic force push-back when faced with animpinging mechanical force. For example, FIG. 75 illustrates anapparatus with one or more mechanical members 7528, 7528′ at the distalend aspiration opening 7521 into the suction lumen 7513 that may exert aforce in a first direction and measure the response force in a reversedirection pushed back by the material.

As mentioned above, in general, any of these sensor types and methodsmay be combined with a force and/or pressure sensor to detect a forceacting on the aspiration opening and/or a negative pressure in theaspiration lumen, which may indicate that something is blocking theaspiration opening; in general, the block may be due to either clotmaterial or vessel wall.

Alternatively or additionally, any of these methods may be used as partof an internal sensor within the suction lumen. For example, FIG. 76illustrates a pair of internal sensors within the lumen 7613 of acatheter that are positioned proximal to the distal aspiration opening7621. The first intra-lumen sensor 7638 in this example may be anelectrical (e.g., impedance) sensor, including a first electrode and asecond electrode. A second intra-lumen sensor 7638′ is shown justproximal to the first intra-lumen sensor 7638, separated by, e.g., 5 cmor less. For example, two pairs of electrodes in close proximity withinthe lumen may be able to measure the velocity of the clot as it passesthrough the lumen, by looking at the difference in time onset of thesignal. The duration of the signal may be used along with that velocityto determine the distance of clot within the lumen and therefore thevolume estimate. This may allow for an estimate of clot volume even inthe case that the velocity of the clot in the lumen is non-constant.

As discussed above, when impedance is used to determine materialproperties at the distal end (e.g., at the aspiration opening) and/orwithin the suction lumen, or multiple frequencies may be used todistinguish the type of material near or in contact with the electrodes.For example, FIGS. 77A-77C illustrate the effect of differentfrequencies of applied alternating current when measuring the magnitudeof impedance for an aspiration opening sensor on either side of anaspiration lumen. For example, FIG. 77A shows the effect of theapplication of 120 Hz, 1 kHz, 10 kHz, 100 kHz, and 1 MHz when theaspiration opening (and sensing electrodes) are in contact with eithervena cava (a model of the vessel wall) 7768 or clot material 7769. Foreach frequency, the percentage of change (% change) of the impedance foreach material compared to blood is shown. In FIG. 77B, the impedancemeasured (in Ohms) of each of blood 7767, vena cava (wall) 7768, or clot7769 are shown for each frequency (120 Hz, 1 kHz, 10 kHz, 100 kHz, 1MHz). Similarly, in FIG. 77C, the impedance measured for each materialat different frequencies is shown. In FIG. 7A-7C the electrodes are partof an aspiration opening sensor in which the electrodes are positionedon the rim of the aspiration opening and suction is applied to securethe material against the aspiration opening sensor.

Similar results are seen when a different impedance sensor electrode isused, as shown in FIGS. 78A-78C. In this example, the electrode is aflat headed probe rather than the annular electrodes shown, e.g., inFIG. 55 or 76 . In FIG. 78A the percentage of change in impedancecompared to blood is shown for both vessel wall 7869 (e.g., vena cavatest tissue) or clot material 7868, at 120 Hz, 1 kHz, 10 kHz, 100 kHzand 1 MHz. In FIG. 78B the impedance measured (in Ohms) of each of blood7867, vena cava (wall) 7868, or clot 7869 are shown for each frequency(120 Hz, 1 kHz, 10 kHz, 100 kHz, 1 MHz). Similarly, in FIG. 78C, theimpedance measured for each material at different frequencies is shown.

In general, in any of these apparatuses and methods, impedance levelsmay vary by the sensor geometry (e.g., flat probe vs tip electrode) butthe general trends remain, and when sensing across the aspirationopening, the frequencies between about 100 Hz (e.g., 120 Hz) and 100 kHz(less than 1 MHz) appeared to work best regardless of the geometry ofthese distal electrodes, and the largest delta was seen at 100 kHz (mostlike actual model).

In general, when measuring impedance in any of the apparatuses andmethods described herein the configuration of the sensor(s) may providefor more robust and effective sensing. FIGS. 79A-79B, 80 and 81A-81Billustrate examples of different configuration of internal impedancesensors that may be used to sense and/or track material within thelumen. For example, FIG. 79A shows a first configuration of an internalelectrical impedance sensor comprising two or more electrodes within thesuction lumen. In this example each sensor is coupled to a wireextending proximally to a coupler that can be coupled to a controllerfor processing, storing and/or transmitting the impedance value(s). Ineach of these examples the suction lumen has an inner diameter of about0.25″ (0.635 cm). In FIG. 79A a pair of at least partially annularelectrodes surround the lumen; the first electrode is separated from thesecond electrode by approximately 1 mm. In FIG. 79B a similararrangement is shown, but with a much larger separation (e.g., 3 mm)between the first and second electrodes, and the first and secondelectrodes in this example may be annular electrodes that extendcompletely (or nearly completely) around the inner lumen. FIG. 80 showsanother example of an internal electrical impedance sensor in which apair of annular electrodes extend as a full ring around the suctionlumen wall and the electrodes are separated by about 5 mm.

Any of these internal electrical impedance sensors may be configured asquad detectors, as shown in FIGS. 81A-81B, having four electrodesdivided in to two sets of two (e.g., two pairs) of electrodes that areseparated by a small distance. In FIG. 81A, the first and secondelectrodes of the first pair of annular electrodes are separated byabout 3 mm and the first and second electrodes of the second pair ofannular electrodes are separated by about 3 mm. The first pair ofannular electrodes are separated from the second pair of annularelectrodes by about 10 mm. this configuration may allow for detection ofthe rate of movement of a material (e.g., clot material) within thesuction lumen from the single quad detector (internal electricalimpedance sensor). FIG. 81B is similar to FIG. 81A but with a separationof about 5 mm between the pairs of annular electrodes.

The various configuration of the internal electrical impedance sensorsshown in FIGS. 79A-79B, 80, and 81A-81B were tested to estimate clotvolume based on the impedance measurements taken with the internalelectrical impedance sensors and the results are shown in the graph ofFIG. 82 . In this example, configuration A corresponds to the exampleshown in FIG. 79A, configuration B corresponds to the example shown inFIG. 79B, configuration D corresponds to the example shown in FIG. 81Aand configuration E corresponds to the example shown in FIG. 81B. As canbe seen in FIG. 82 , all of these variations had similar results.

FIGS. 83 and 84 illustrate tracking of clot material using differentinternal electrical impedance sensors similar to those shown in FIGS.79A-79B, 80 and 81A-81B. In FIG. 83 , the impedance over time wasmonitored when the apparatus removed clot material through the suctionlumen using different configurations of internal impedance sensors. Forexample the signal 8301, 8401 from an internal impedance sensor such asthe one shown in FIG. 79A is similar to that shown by the signal 8303,8403 from internal impedance sensor such as the one shown in FIG. 79B.Each of the internal impedance sensors configured as quaddetector/sensors returned two signals that are slightly delayed in time(reflecting the travel time). For example the internal impedance sensorof FIG. 81A returned signals 8305, 8405 and 8307, 8407 that are slightlyoffset. Similarly, an impedance sensor such as that shown in FIG. 81Breturned signals 8309, 9409 and 8311, 8411. In this example theimpedance showed removal of clot material that stayed fairly organizedas it traveled down the length of the suction lumen. In contrast, inFIG. 84 , the clot material can be observed to break apart during traveldown the suction lumen. In this example, when clot breaks up, the clotvolume estimation may be highly variable, as clot volume determinationmay depend in part on the rate of travel of the clot material as well asthe spacing of the electrodes. Further, clot packing may affect theability to estimate clot volume and transit velocity, and impedanceamplitude may be higher when clot breaks up, as shown in FIG. 84 .

In any of the apparatuses and methods described herein, the size of clotmaterial (which may be further estimated from the known cross-sectionalarea of the suction lumen, as well as the length of the clot material),the rate of travel of the clot material within the lumen, the presenceor absence of clot material clogged within the suction catheter, etc.may be determined and output to a user, stored, transmitted and/orfurther processed.

FIG. 85 shows one example of an apparatus as described herein includingmany of the features described above. For example, FIG. 85 includes aflexible elongate body 8513 (shown in two parts) that includes a distalend region 8577 with a guide channel 8531 for a diagnostic catheter 8537(and/or guidewire) extending from a distal end opening through thelength of the elongate body. The distal end region may include anextraction chamber region having an aspiration opening 8521 into asuction lumen that extends along the length of the flexible elongatebody. The aspiration opening at the distal end region of the flexibleelongate body in this example is side-facing (e.g., on a tapered distalend region). The distal end region may also include one or more openinginto the suction lumen on a side of the distal end region that isopposite from the aspiration opening (not visible in FIG. 85 ).

The distal end of the apparatus also includes an aspiration openingsensor comprising two electrodes 8558, 8558′ positioned at a rim of theaspiration opening. In this example the electrodes are positioned at the2 o'clock and 10 o'clock position, generally towards the proximal end ofthe aspiration opening. The electrodes of the aspiration opening sensormay be between about 0.1 and 3 cm (e.g., between about 0.5 and 2 cm,etc.) long (around the perimeter of the aspiration opening). In general,it may be helpful to sensing material in contact with the aspirationopening to position these electrodes in the proximal half (e.g., theproximal 40%, proximal 35%, proximal 30%, etc., such as between the 9o'clock and 3 o'clock, or more preferably between 10 o'clock and 2o'clock, or between 11 o'clock and 1 o'clock positions), as this is theregion of highest flow density into the aspiration opening. A second setof internal impedance sensing electrodes 8507, 8507′ are positioned justproximal to the aspiration opening and the aspiration opening sensorelectrodes 8558, 8558′. The second set of internal impedance sensingelectrodes may be configured to detect material (e.g., clot material)within the suction lumen and may be used in conjunction (or coordinated)with the aspiration opening sensor electrodes to confirm that theaspiration opening is in contact with clot material, or to distinguishfrom vessel wall when force (e.g., suction) is applied to drive thedistal end region, including the aspiration opening, into a material.The internal impedance sensing electrodes may be spaced from theaspiration opening (proximal end) by between about 0.1 and 30 mm (e.g.,between about 1 and 20 mm, between about 1 and 10 mm, etc.). Theinternal impedance sensing electrodes in this example includes twoannular electrodes, extending partially around the wall of the suctionlumen, but any shape electrode may be used. The internal impedancesensing electrodes may be separated from each other by any appropriatedistance, e.g., between about 0.1 and 10 mm (e.g., between about 0.5 and5 mm, 0.5 and 3 mm, etc.). The internal impedance sensing electrodesshown in FIG. 85 have a diameter (in the proximal-to-distal direction)of about 1 mm each.

The internal impedance sensing electrodes and the aspiration openingsensor electrodes may each be electrically coupled to an electricalline, wire, trace, etc., extending proximally down the length of theflexible elongate body and into the proximal handle 8509. In the exampleapparatus shown in FIG. 85 , a second internal impedance sensor,configured as a quad detector/sensor including two sets of two internalimpedance sensing electrodes 8536, 8536′, 8537, 8537′. The secondinternal impedance sensor is still within the suction lumen, but ispositioned within the portion of the suction lumen in the handle. Thesuction lumen may extend from the elongate body into the handle and mayinclude a suction port 8597 at the proximal end.

In FIG. 85 the apparatus also includes a controller 8515 that couples orconnects (via a connector 8587 to each of the electrodes of the internalimpedance sensor (e.g., first and second internal impedance sensors) andthe aspiration opening sensor. The controller in this example includesone or more outputs (e.g., display/LED, lights, tone/sound, etc.) and isconfigured to track material within the suction lumen. The controllermay indicate (by a first LED) that material is within the distal end ofthe suction lumen and/or at the aspiration opening. For example, thecontroller may process impedance signals (received following theapplication of a current to the distal internal impedance sensor and/oraspiration opening sensor) to determine if or when the impedance isgreater than a threshold indicating the likelihood of material (e.g.,clot material) rather than blood and/or vessel wall in the internalimpedance sensor and/or the aspiration opening sensor. The controllermay also indicate (e.g., by a second LED) that material has passed (oris positioned proximal to) the proximal sensor, such as a quaddetector/sensor shown in FIG. 85 . In some example, the controller mayindicate that the material has passed and/or is nearby when the changein impedance (relative to the impedance in blood) exceeds a threshold.In some examples, the controller may determine a flow rate of the clotmaterial by tracking the impedance change between the two pairs ofelectrodes at a known (e.g., 10 mm) distance, and may estimate a totalvolume of material passing through the proximal end (and out of theapparatus) based on the flow rate, as well as the total size of the clotmaterial (e.g., the product of the time clot material is detected andthe flow rate, as well as the known cross-sectional area of the suctionlumen at the region of the second internal impedance sensor). Thecontroller may display an estimate of the volume and/or may store,transmit or otherwise process this information.

When a feature or element is herein referred to as being “on” anotherfeature or element, it can be directly on the other feature or elementor intervening features and/or elements may also be present. Incontrast, when a feature or element is referred to as being “directlyon” another feature or element, there are no intervening features orelements present. It will also be understood that, when a feature orelement is referred to as being “connected”, “attached” or “coupled” toanother feature or element, it can be directly connected, attached orcoupled to the other feature or element or intervening features orelements may be present. In contrast, when a feature or element isreferred to as being “directly connected”, “directly attached” or“directly coupled” to another feature or element, there are nointervening features or elements present. Although described or shownwith respect to one embodiment, the features and elements so describedor shown can apply to other embodiments. It will also be appreciated bythose of skill in the art that references to a structure or feature thatis disposed “adjacent” another feature may have portions that overlap orunderlie the adjacent feature.

Terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention.For example, as used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, steps, operations, elements, components, and/orgroups thereof. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items and may beabbreviated as “/”.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if a device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of over and under. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly”, “downwardly”, “vertical”, “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

Although the terms “first” and “second” may be used herein to describevarious features/elements (including steps), these features/elementsshould not be limited by these terms, unless the context indicatesotherwise. These terms may be used to distinguish one feature/elementfrom another feature/element. Thus, a first feature/element discussedbelow could be termed a second feature/element, and similarly, a secondfeature/element discussed below could be termed a first feature/elementwithout departing from the teachings of the present invention.

Throughout this specification and the claims which follow, unless thecontext requires otherwise, the word “comprise”, and variations such as“comprises” and “comprising” means various components can be co-jointlyemployed in the methods and articles (e.g., compositions and apparatusesincluding device and methods). For example, the term “comprising” willbe understood to imply the inclusion of any stated elements or steps butnot the exclusion of any other elements or steps.

In general, any of the apparatuses and methods described herein shouldbe understood to be inclusive, but all or a sub-set of the componentsand/or steps may alternatively be exclusive and may be expressed as“consisting of” or alternatively “consisting essentially of” the variouscomponents, steps, sub-components or sub-steps.

As used herein in the specification and claims, including as used in theexamples and unless otherwise expressly specified, all numbers may beread as if prefaced by the word “about” or “approximately,” even if theterm does not expressly appear. The phrase “about” or “approximately”may be used when describing magnitude and/or position to indicate thatthe value and/or position described is within a reasonable expectedrange of values and/or positions. For example, a numeric value may havea value that is +/−0.1% of the stated value (or range of values), +/−1%of the stated value (or range of values), +/−2% of the stated value (orrange of values), +/−5% of the stated value (or range of values), +/−10%of the stated value (or range of values), etc. Any numerical valuesgiven herein should also be understood to include about or approximatelythat value, unless the context indicates otherwise. For example, if thevalue “10” is disclosed, then “about 10” is also disclosed. Anynumerical range recited herein is intended to include all sub-rangessubsumed therein. It is also understood that when a value is disclosedthat “less than or equal to” the value, “greater than or equal to thevalue” and possible ranges between values are also disclosed, asappropriately understood by the skilled artisan. For example, if thevalue “X” is disclosed the “less than or equal to X” as well as “greaterthan or equal to X” (e.g., where X is a numerical value) is alsodisclosed. It is also understood that the throughout the application,data is provided in a number of different formats, and that this data,represents endpoints and starting points, and ranges for any combinationof the data points. For example, if a particular data point “10” and aparticular data point “15” are disclosed, it is understood that greaterthan, greater than or equal to, less than, less than or equal to, andequal to 10 and 15 are considered disclosed as well as between 10 and15. It is also understood that each unit between two particular unitsare also disclosed. For example, if 10 and 15 are disclosed, then 11,12, 13, and 14 are also disclosed.

Although various illustrative embodiments are described above, any of anumber of changes may be made to various embodiments without departingfrom the scope of the invention as described by the claims. For example,the order in which various described method steps are performed mayoften be changed in alternative embodiments, and in other alternativeembodiments one or more method steps may be skipped altogether. Optionalfeatures of various device and system embodiments may be included insome embodiments and not in others. Therefore, the foregoing descriptionis provided primarily for exemplary purposes and should not beinterpreted to limit the scope of the invention as it is set forth inthe claims.

The examples and illustrations included herein show, by way ofillustration and not of limitation, specific embodiments in which thesubject matter may be practiced. As mentioned, other embodiments may beutilized and derived there from, such that structural and logicalsubstitutions and changes may be made without departing from the scopeof this disclosure. Such embodiments of the inventive subject matter maybe referred to herein individually or collectively by the term“invention” merely for convenience and without intending to voluntarilylimit the scope of this application to any single invention or inventiveconcept, if more than one is, in fact, disclosed. Thus, althoughspecific embodiments have been illustrated and described herein, anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the above description.

What is claimed is:
 1. An apparatus comprising: a flexible elongate bodyhaving a suction lumen extending therethrough; an aspiration openinginto the suction lumen at a distal end region of the flexible elongatebody; an aspiration opening sensor comprising two or more electrodespositioned on a rim of the aspiration opening; and a controller coupledto the aspiration opening sensor and configured to distinguish betweenclot and blood based on an impedance signal between the two or moreelectrodes.
 2. The apparatus of claim 1, wherein the controllercomprises sensing circuitry configured to distinguish between clot andblood based on the impedance signal between the two or more electrodes.3. The apparatus of claim 1, wherein the controller is configured todistinguish between clot and blood when a negative pressure is applied.4. The apparatus of claim 1, wherein the controller is configured todistinguish between clot and blood when a mechanical force is appliedagainst the aspiration opening.
 5. The apparatus of claim 1, wherein theaspiration opening is on a tapered side of the distal end region of theflexible elongate body.
 6. The apparatus of claim 1, wherein the two ormore electrodes of the aspiration opening sensor are recessed from therim.
 7. The apparatus of claim 1, wherein the two or more electrodes ofthe aspiration opening sensor are spaced equally apart from each otheron the rim of the aspiration opening.
 8. The apparatus of claim 1,wherein the two or more electrodes of the aspiration opening sensor arepositioned opposite each other across the aspiration opening.
 9. Theapparatus of claim 1, wherein the two or more electrodes of theaspiration opening sensor are positioned on the rim of the aspirationopening between an 11 o'clock position and a 1 o'clock position relativeto the aspiration opening.
 10. The apparatus of claim 1, furthercomprising a plurality of smaller flow-modifying openings into thesuction lumen positioned adjacent to the aspiration opening.
 11. Theapparatus of claim 10, further comprising a second sensor positionedwithin the suction lumen of the flexible elongate body.
 12. An apparatuscomprising: a flexible elongate body having a suction lumen extendingtherethrough; an aspiration opening into the suction lumen on a taperedside of a distal end region of the flexible elongate body; an aspirationopening sensor comprising two or more electrodes positioned on aproximal half of a rim of the aspiration opening; and a controllercoupled to the aspiration opening sensor and configured to distinguishbetween clot and blood based on an impedance signal between the two ormore electrodes.
 13. An apparatus comprising: a flexible elongate bodyhaving a suction lumen extending therethrough; an aspiration openinginto the suction lumen on a tapered side of a distal end region of theflexible elongate body; an aspiration opening sensor comprising two ormore electrodes positioned on a rim of the aspiration opening; and aproximal suction port in communication with the suction lumen; andwherein the two or more electrodes of the aspiration opening sensor areconfigured to couple to a controller to provide electrical impedanceinput to distinguish between clot and blood.
 14. The apparatus of claim13, further comprising a second sensor at the distal end region.
 15. Theapparatus of claim 14, wherein the second sensor is within the suctionlumen.
 16. The apparatus of claim 13, wherein the two or more electrodesof the aspiration opening sensor are recessed from the rim.
 17. Theapparatus of claim 13, wherein the two or more electrodes of theaspiration opening sensor are spaced equally apart from each other onthe rim of the aspiration opening.
 18. The apparatus of claim 13,wherein the two or more electrodes of the aspiration opening sensor arepositioned opposite each other across the aspiration opening.
 19. Theapparatus of claim 13, wherein the two or more electrodes of theaspiration opening sensor are positioned on a proximal half of the rimof the aspiration opening between an 11 o'clock position and a 1 o'clockposition relative to the aspiration opening, wherein a 12 o'clockposition is a proximal-most region of the rim of the aspiration opening.20. The apparatus of claim 13, further comprising a plurality of smallerflow-modifying openings into the suction lumen positioned adjacent tothe aspiration opening.
 21. A method of distinguishing a blood clot fromblood, the method comprising: advancing a flexible elongate catheterhaving a suction lumen within a blood vessel, wherein the flexibleelongate catheter comprises an aspiration opening into the suction lumenat a distal end region of the flexible elongate catheter and two or moreelectrodes on the aspiration opening; and determining if the aspirationopening is engaged with a blood clot or with blood based on an impedancemeasured from the two or more electrodes at or adjacent to theaspiration opening.
 22. The method of claim 21, wherein determiningcomprises applying negative pressure within the suction lumen.
 23. Themethod of claim 21, further comprising indicating that the aspirationopening is engaged with blood clot.
 24. The method of claim 21, furthercomprising applying alternating current having a frequency of betweenabout 1 kHz and 1 MHz.
 25. The method of claim 24, wherein thealternating current has a frequency of between about 10 kHz and 100 kHz.26. The method of claim 21, further comprising delaying the step ofdetermining if the aspiration opening is engaged with a blood clot orwith blood for a delay period after a force is applied.
 27. The methodof claim 21, wherein determining if the aspiration opening is engagedwith blood clot or with blood is based on both an impedance measurementsfrom the two or more electrodes at or adjacent to the aspiration openingand a second sensor positioned within the suction lumen of the flexibleelongate catheter.
 28. The method of claim 21, further comprisingadjusting suction through the suction lumen based on the impedancemeasured from the two or more electrodes at or adjacent to theaspiration opening.
 29. The method of claim 21, further comprisingapplying negative pressure within the suction lumen and confirming thatblood clot material has been cleared through the suction lumen.